Objective: In Japan, healthcare professionals are required to report the adverse drug events that occur with the use of medicines to the Minister of Health, Labor, and Welfare. The reported information is collected in the Japanese Adverse Drug Event Report database (JADER) and is freely available. There are no reports that evaluated the adverse events (AEs) in JADER based on the need for a physician’s diagnosis. This study classified AEs by pharmacists or physicians in JADER based on the need for a physician’s diagnosis and evaluated the differences in their contents.Methods: AEs reported by pharmacists, physicians, pharmacists and physicians in the economic years 2004 to 2017 in JADER were collected annually, and the trends were compared. The AEs of methotrexate in 2017 were classified into two groups based on the need for a physician’s diagnosis. The necessity of a physician’s diagnosis was judged by two senior pharmacists and compared using the chi-squared test.Results: The number of AEs reported by pharmacists and physicians from 2004 to 2017 increased from 689 to 7,127 and from 20,933 to 39,382, respectively. Among the AEs of methotrexate in 2017, AEs requiring physician’s diagnosis reported by pharmacists were 337 events and physicians were 2,413 events. Whereas, AEs that did not require a physician’s diagnosis reported by pharmacists were 172 events and physicians were 321 events. Physicians had significantly more AEs requiring diagnosis than pharmacists did (p＜ 0.0001).Conclusion: The reports of pharmacists with JADER have fewer AEs with the diagnosis than those of physicians.