Background: It is an important study to investigate incident reports submitted by multidisciplinaries in the Special Functioning Hospitals of Japan. We clarify the characteristics of the incidents and evaluate the outcomes obtained from a polygonal analysis. Material and Methods: We collected 1638 incident reports submitted by multidisciplinaries for one year from April, 2016 to March, 2017. The incidents were retrospectively analyzed by profile, levels, distribution, and ratios. Results: The majority of incidents (94.7%, 1551/1638) were distributed between the levels 0 to 3a, on the other hand, the incidents of a level higher than 3b occupied 5.3%. The reports from nurses were 75.3% (1234/1638) and those from doctors were 12.8% (209/1638). The level 3b totalled 30.6% (64/209) of the doctor-reported incidents. In contrast, the level 2 totalled 33.8% (417/1234) of the nurse-reported incidents. The levels of the doctor-incidents were comparatively higher than those of the nurse-incidents. The profiles of the incidents were categorized as drug administration (n = 439, 26.8%), nursing care (n = 399, 24.4%), drain and tube (n = 258, 15.8%), medical treatment and care (n = 199, 12.1%), medical examination (n = 141, 8.6%), medical equipment (n = 99, 6.0%), giving instructions (n = 66, 4.0%) and blood transfusion (n = 12, 0.7%). Conclusions: It is important for multidisciplinaries to report incidents because they can learn novel experiences from the incidents for preventing a recurrence. By proper utilizing of the incident-reporting system, it could be an effective tool that helps the medical staff build a strong patient safety culture,