In recent years, the prices of new smartphones have soared, leading to a rapid increase in demand for used smartphones.

However, with many purchasing options available, many people are unsure where to buy and worry about what to do if the device breaks down quickly.

【Conclusion】
Used smartphones are an attractive option that can save you money compared to new ones, and they are perfectly usable for daily life. However, "where you buy" is the most crucial point. Check for warranties, condition descriptions, and sales records, and choose a reputable shop.

In this article, we will provide an honest review of recommended shops for used smartphones. Please read until the end.

Checkpoints when buying a used smartphone

To safely purchase a used smartphone, check the following points:

• IMEI number and network usage restrictions

• SIM lock and SIM standard

• Is battery capacity/condition clearly stated?

• Accessories, scratches, and signs of use on the main unit

We will explain each point.

IMEI number and network usage restrictions

Before purchasing, check the IMEI number and ensure that network usage restrictions are indicated as "〇" (no restrictions). If the restriction is "△" or "×", there is a risk that communication may become unavailable.

Even if you cannot check the IMEI number before purchase, if the shop offers a "network usage restriction guarantee" or "red-ROM guarantee," you can purchase with peace of mind, as they will provide a replacement or similar support if restrictions are imposed.

[Network Usage Restriction Confirmation Sites]

au・docomo・SoftBank

Check PRODIG's Red ROM Guarantee and other secure warranty systems.

SIM lock and SIM standard

Always check for SIM unlock. If a SIM lock is present, the device can only be used with a specific carrier's network, meaning it might not be usable immediately after purchase.

Also, it's essential to check if the SIM standard (nanoSIM, eSIM, etc.) of the smartphone matches the SIM card you intend to use. Make sure your current SIM is compatible before making a purchase.

For information on how to check and unlock SIM locks, please refer to the following article:

[Used iPhone] Explaining How to Check the SIM Unlock Code

Is battery capacity/condition clearly stated?

Used smartphones often have degraded batteries, so when purchasing, check if the maximum battery capacity and condition are stated.

Ideally, it's safer to choose a device with a battery condition of "80% or more." Smartphones with a battery condition below 80% are more likely to experience issues such as the battery draining quickly or slow charging over a day's use.

For more details on battery capacity, please refer to the following article:

What is the Battery Capacity of a Used Smartphone? Also Check Maximum Capacity.

Accessories, scratches, and signs of use on the main unit

The physical condition, such as whether there are noticeable scratches on the body or the state of the LCD, is an important factor. Also, check if accessories like the charger and earphones are included.

Carefully examine photos and product descriptions; choosing items with "actual product images" makes it easier to assess the condition.

For sites where you cannot inspect the actual item, refer to the product rank.

"Unused" or "A-rank" items often have minimal signs of use and are like new. While the price may be higher, the peace of mind and satisfaction regarding quality are greater, leading to less regret.

Where to buy a used smartphone?｜Pros and Cons explained

Used smartphones can be purchased from physical stores, specialized used smartphone shops, online shops, and flea market apps. Here, we explain the advantages and disadvantages of each purchasing option.

Brick-and-mortar stores (electronics retailers, carrier shops, etc.)

At physical stores, you can inspect the actual smartphone and its condition firsthand. You can check screen scratches and button responsiveness on the spot, and consult staff directly. Since you can take the device home immediately, it's convenient if you need a smartphone urgently.

However, prices tend to be higher compared to online shopping, and stock and model variety may be limited.

This option is recommended for those who value the reassurance of checking the actual item and need a smartphone quickly.

Specialized Used Smartphone Stores (e.g., PRODIG)

Specialized used smartphone stores are characterized by their extensive product lineup and clear condition rankings. They offer robust warranties and functional checks, allowing even beginners to purchase with peace of mind. Many stores operate both online and physical locations, catering to various needs.

However, there may not be stores in many areas. Additionally, popular models can sell out quickly after being stocked.

Smartphone specialty stores are recommended for those who prioritize quality and warranty.

Online Shops (major e-commerce sites, used smartphone mail-order sites, etc.)

Online shops offer the convenience of ordering 24/7 and the ability to compare shops nationwide. By utilizing sales and point rewards, you might even be able to purchase a smartphone significantly cheaper than a new one.

However, since you cannot physically inspect the smartphone, there is a risk that the actual condition may differ from the description or photos. It is important to check the return and exchange policies beforehand and choose a trustworthy seller or store.

Flea Market Apps (Mercari, Yahoo Auctions, etc.)

Flea market apps offer a higher chance of finding used smartphones at a lower price than retail stores, and you might even discover rare models or colors.

The ability to negotiate prices is also attractive, but a major drawback is the almost complete lack of warranty and the high risk of malfunctions or scams. You also need to handle transactions and shipping yourself, which can be a bit daunting for beginners.

If you prioritize safety over price, it's safer to choose another purchasing option.

Clear at a glance with a comparison table! Differences among recommended shops

*Prices are based on research of each company's online store as of August 2025.

PRODIG is distinguished by its 180-day long-term warranty and unique, stringent inspection system. It will be a strong option for those buying a used smartphone for the first time or who want to use it with peace of mind for a long time.

Companies A and B have established track records as major players in the industry, while Company C may offer good deals when combined with point rewards. Compare their respective features and choose the shop that best suits your needs.

Carriers tend to be more expensive, but they offer comprehensive manufacturer warranties and repair support, making them ideal for those who prioritize peace of mind above all else.

If you're buying a used smartphone, choose "PRODIG"!

[Recommended Points]

• Comes with a 180-day warranty and comprehensive after-sales service.

• Has its own strict quality standards, with ranks clearly indicated.

• A rich lineup where even scarce models can be found.

PRODIG is a specialized used smartphone store characterized by strict quality standards and a thorough inspection system. All products come with a 180-day warranty, and they promptly handle any post-purchase issues.

They stock a wide range of popular models that are often in short supply, and detailed information such as condition rank and battery capacity is clearly stated. Online purchases are also straightforward, making it a reliable choice even for first-time used smartphone buyers.

PRODIG is a full member of Re-Use Mobile Japan (RMJ) and manages its products based on strict quality standards. Additionally, they regularly offer extensive warranty programs and sales on popular models.

If you have any questions regarding the use of PRODIG, please feel free to contact us at the details below.

Phone number: 03-6435-5045

Available hours: 11:00 AM - 6:00 PM

Q&A｜Common questions about buying used smartphones answered

How much should I worry about battery degradation?

Used smartphones may have lower battery performance than new ones. As a guideline, a maximum capacity of 80% or more usually won't significantly hinder daily use, but if it's in the 70% range, you'll likely feel stressed due to increased charging frequency. Check the capacity and whether replacement is possible before purchasing.

For more details on battery capacity, please refer to the following article:

[2025 Edition] Used Smartphone Battery: Aim for "80%"! How to Relieve Anxiety and Choose Wisely

Is security okay with used smartphones?

If purchased from a reputable seller, thorough initialization and operational checks are performed, minimizing security risks. However, with flea market apps or private transactions, data erasure might be incomplete, so caution is advised. After purchase, it's crucial to keep the OS and apps updated.

For characteristics of trustworthy stores, please refer to this article.

Is SIM lock still a thing? What should I be aware of when buying?

While SIM locks were abolished in principle for new models released after 2021, some older models in the used market may still have them. It's especially important to check older models. When purchasing, always look for "SIM-free" or "unlocked" indications.

For information on how to check and unlock SIM locks, please refer to the following article:

[Used iPhone] Explaining How to Check the SIM Unlock Code