Interprofessional education (IPE) for medical students is becoming increasingly important, as reflected in the increasing number of medical schools adopting IPE. However, the current status of and barriers to pre-registration IPE implementation in Japanese medical schools remain unknown. The purpose of this study was to clarify the status and barriers of IPE implementation in medical schools in Japan. We conducted a curriculum survey from September to December 2016 of all 81 medical schools in Japan. We mailed the questionnaire and asked the schools' undergraduate education staff to respond. The survey items were the IPE implementation status and barriers to program implementation. Sixty-four of the 81 schools responded (response rate 79.0%), of which 46 (71.9%) had implemented IPE, 42 (89.1%) as compulsory programs. Half of IPE programs were implemented in the first 2 years, while less than 10% were implemented in the latter years of medical programs. As part of the IPE programs, medical students collaborated with a wide range of professional student groups. The most common learning strategy was lectures. However, one-third of IPE programs used didactic lectures without interaction between multi-professional students. The most common perceived major barrier to implementing IPE was adjustment of the academic calendar and schedule (82.8%), followed by insufficient staff numbers (73.4%). Our findings indicate that IPE is being promoted in undergraduate education at medical schools in Japan. IPE programs differed according to the circumstances of each school. Barriers to IPE may be resolved by improving learning methods, introducing group discussions between multi-professional students in lectures or introducing IPE programs using team-based learning. In summary, we demonstrated the current status and barriers of IPE implementation in Japanese medical schools. Our findings will likely lead to the promotion of IPE programs in Japan.