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Using a Secondhand or Overseas Phone in Japan

✓ Last verified 2026-09-09 Sources: 5 sites 7 min read

The short version

A used iPhone on Mercari looks like a bargain until a comment thread mentions "giteki" and legality in the same sentence, and the listing itself says nothing about it. The same question comes up for anyone planning to bring a phone from home rather than buying one locally: does inserting a Japanese SIM into a device built for another country's networks cause a problem here? This guide walks through what the technical conformity mark actually covers, how to check your own device, and where the SIM itself might still be locked to its original carrier.

What the mark actually certifies

Japan's Radio Act requires radio-transmitting equipment, which includes any phone with cellular or Wi-Fi hardware, to meet the country's technical standards before it can be used to transmit here. Certification is shown as a small mark printed on the device or, on modern smartphones and tablets, displayed digitally in a settings screen instead of etched into the casing. It's a technical equipment standard, not a statement about who owns the phone or how they acquired it — a secondhand handset carries whatever certification it shipped with, unaffected by changing hands on Mercari or Jimoty.

Many phones aimed at a global market, including recent iPhone and Galaxy flagship models, already hold Japanese certification because manufacturers apply for it as part of selling into the Japanese market in the first place. That means the giteki question is often moot for a mainstream secondhand phone — it's worth checking before assuming a gap exists.

Check your device before anything else

Where to look

  1. 1 iPhone: Settings → General → Legal & Regulatory Look for a Japan-specific certification number in the regulatory information listed there. Its presence means the device already meets the requirement.
  2. 2 Android: Settings → About phone → Regulatory labels (naming varies by manufacturer) Some manufacturers label this screen "Regulatory information" or bury it under a similar settings path; a model-specific search helps if it isn't obvious.
  3. 3 Still unsure? Search the model directly The Ministry of Internal Affairs and Communications runs a public search tool for devices that hold technical conformity certification, searchable by certificate number or, on some models, by name. It's the authoritative source, not a blog summary — including this one.

If the mark isn't there: the FCC/CE exception, and its limits

A 2016 change to Japan's telecommunications rules created a carve-out for devices that already carry FCC certification (the US standard) or a CE mark (the EU standard) but lack Japanese certification. Under certain conditions, these devices can be used in Japan without the giteki mark. Sources disagree on exactly how far that carve-out reaches. Some describe it as covering international roaming and Wi-Fi use for visitors within a 90-day window. Others describe FCC- or CE-certified phones as usable with a Japanese SIM for calls and data with no such time limit. We didn't find a single explanation clean enough to flatten into one rule for every reader, and a best guess dressed up as a verdict would do you a disservice on a question the Radio Act actually polices.

Two places settle it more reliably than any summary can: the ministry's device search tool confirms whether your specific model already has full Japanese certification, which sidesteps the question entirely, and the carrier or MVNO whose SIM you're about to insert can tell you directly whether they'll activate that model on their network. If you're settling in for the long term rather than passing through, lean on the second option before you commit to a plan built around a device without the mark.

The SIM lock is a separate question

None of the above touches whether the SIM slot itself will accept just any SIM card — that's a carrier restriction, not a radio-law one, and it applies to Japanese-market phones too. A guideline from the Ministry of Internal Affairs and Communications took effect in October 2021 requiring carriers to sell new phones unlocked by default, so a phone bought new in Japan afterward is generally already SIM-free. Older models, phones bought before the guideline, and secondhand devices from anywhere can still be locked.

Checking and clearing a SIM lock

  1. 1 iPhone: check under Settings → General → About A "No SIM restrictions" line means the phone is unlocked. A carrier name listed instead points to a lock tied to that network.
  2. 2 Android: check the SIM status in network settings, or just try a different SIM Menu names vary by manufacturer; inserting a SIM from a different carrier and watching for a lock-related error message is the fastest practical test.
  3. 3 If it's locked, the original carrier unlocks it Major Japanese carriers offer online unlock requests, usually free, tied to the device's IMEI number and sometimes a minimum ownership period. A secondhand phone bought from an individual seller may need that seller's account details or a shop that handles unlocking as a paid service instead.

Where this fits

This guide sits between two others on this site rather than replacing either. If you're weighing a Mercari or Jimoty phone purchase in the first place, our guide to buying secondhand on Mercari and Jimoty covers the platforms themselves, payment safety, and pickup logistics — phones raise the certification question this page answers, on top of everything that guide already covers for secondhand shopping generally. And if a secondhand or imported device turns out not to be the right fit, our guide to getting a new phone contract in Japan covers buying a device from a carrier directly, with the certification question already settled by the manufacturer.

Where this guide stops

This page explains the general framework, not a ruling on your phone. Certification status depends on the exact model and its manufacturing history, the FCC/CE exception's practical scope is described unevenly even across Japanese-language sources, and carrier unlock policies change. For an actual determination, the ministry's search tool and a direct question to your intended carrier or MVNO carry more weight than anything summarized here.

This article provides general information only and is not a determination of whether any specific device may legally be used in Japan. Technical conformity requirements are enforced under Japan's Radio Act; confirm your device's certification status using the Ministry of Internal Affairs and Communications' own search tool, and confirm SIM compatibility with your carrier or MVNO before relying on either. See our disclaimer for more.

Sources

Confirmed via search engine results on 2026-09-09. This working environment's direct fetch of the domains below, including the ministry's own site, was blocked by the network's egress policy while writing this article, so the explanation above is cross-checked across multiple independent sources rather than a single direct read of the primary regulation — and, on the scope of the FCC/CE exception specifically, those sources did not fully agree with each other, which is reflected in the hedged wording above rather than smoothed over.

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