Several prefectures in Japan, including Tokyo and Kanagawa, prohibit the use of earphones while cycling under local ordinances. This is because wearing earphones can make it difficult to hear surrounding sounds and voices, which could hinder safe cycling. In fact, there have been several accidents resulting in fatalities where cyclists wearing earphones collided with pedestrians.
Furthermore, although the Road Traffic Act (a national law) does not explicitly prohibit the use of earphones, cycling while unable to grasp the surrounding situation due to earphone use may constitute a violation of the safe driving obligation. (And, if you are listening to music with earphones, you may be committing this violation.)
Until now, there has been limited enforcement of traffic violations by cyclists. This is because applying penalties under the Road Traffic Act to minor violations can result in a criminal record (criminal fine called BAKKIN), which is considered disproportionate. However, a penalty system similar to that for automobiles will be introduced for cyclists by 2026. This system will impose fines (traffic violation fine called HANSOKUKIN) without resulting in a criminal record. This makes it easier for police to enforce the law, leading to increased enforcement.
While bicycles are a convenient means of transportation, they are classified as light vehicles under the Road Traffic Act and require adherence to traffic rules, just like automobiles. Using earphones can endanger not only yourself but also surrounding pedestrians and vehicles. Please comply with traffic rules and strive for safe cycling.