The present study aimed to identify factors associated with retention in HIV/AIDS care among migrant patients who visited the outpatient clinic of the AIDS Clinical Center, National Center for Global Health and Medicine in Tokyo, Japan. We reviewed the records of 551 selected (78 non-Japanese and 473 Japanese) patients who started visiting our clinic between 2011 and 2014. A total of 390 patients (70.8%: 38 non-Japanese and 352 Japanese) continued their visits during the study: from the date of their first visit to the end of 2015. The difference in retention rate was not significant (Incidence Rate Ratio (IRR) = 0.89, p = 0.27), but the loss-to-follow-up cases were considerably high among non-Japanese patients (n = 13, Incidence rate (IR) = 24.6 per 100,000 person-days, IRR = 3.65, p<0.01 after adjusting for time since diagnosis). The results showed, nevertheless, that there was no apparent association between retention and factors peculiar to non-Japanese. Twelve out of thirteen lost-to-follow-up non-Japanese patients held legal status to reside in Japan and were eligible for public health services. Nine had limited fluency in Japanese language, and six used alternative verbal communication. Further studies are needed to identify the factors responsible for the high dropout rate and to improve the care of migrant patients living with HIV/AIDS.