Binge drinking by college students is a problematic behavior. However, data on binge drinking and the reasons for drinking by college students in Japan are scarce. We explored the reasons for drinking among college students. The study used a cross-sectional design and a self-administered questionnaire. From December 2016 to March 2017, we sampled undergraduate and graduate students aged 20 or older at 35 colleges in the Kanto region of Japan. The questionnaire addressed 1) frequency of drinking alcohol, 2) amount of drinking per day, 3) frequency of binge drinking in the past year, and 4) reasons for drinking (with 12 possible responses). The t-test was used to compare the means between binge drinkers and non-binge drinkers. Logistic regression analysis was conducted on binge drinking and the reasons for drinking. The participants included 303 men and 260 women. Significant differences between men and women included the presence of binge drinking (men: 74.9%; women: 59.6%). Among male students, the statistically significant reasons given for binge drinking were "to feel happy or be in a good mood" and "to relieve stress," whereas among female students, the reasons were "to feel happy or be in a good mood," "to facilitate interpersonal relationships," "to forget something bad," and "to relieve stress." The reasons for drinking associated with binge drinking were identified. It is important to incorporate these results into preventive education about binge drinking aimed at college students in Japan.