OBJECTIVE To investigate the perception and actual use of mobile phones among Japanese high school students while riding their bicycles, and their experience of bicycle crash/near-crash. METHODS A questionnaire survey was carried out at high schools that were, at the time of the survey, commissioned by the National Agency for the Advancement of Sports and Health to conduct school safety research. RESULTS In the survey, we found that mobile phone use while riding a bicycle was quite common among the students during their commute, but those who have a higher perception of danger in this practice, and those who perceived that this practice is prohibited, were less likely to engage in this practice. Male students and students commuting to school by bicycle only were more likely to have used phones while riding. There was a significant relationship between phone usage while riding a bicycle and the experience of bicycle crash/near-crash, although its causality was not established. Bicycle crash/near-crash experienced while using a phone was less prevalent among the students who had a higher perception of danger in phone usage while riding, students who perceived that this practice is prohibited, and students with a shorter travel time by bicycle during the commute. CONCLUSIONS Since mobile phone use while riding a bicycle potentially increases crash risk among cyclists, student bicycle commuters should be made aware of this risk. Moreover, they should be informed that cyclists' phone usage while riding is prohibited according to the road traffic law.