The toxicity test of onion coat colorant (OC), a food colorant extracted from onion (Allium cepa L.), was undertaken using (C57BL/6 × C3H)F1mice of both sexes for the safety assessment of this product. The acute toxicity test was performed by administration of OC suspended in corn oil by gavage at doses of 2500, 5000, 7500, and 10,000 mg/kg body weight to groups of 5 or 6 males and 6 or 7 females, maintained for 14 d. Six of 12 females dosed at 10,000 mg/kg body weight and 3 of 11 females dosed at 7500 mg/kg body weight were dead before the end of the study, indicating that the tolerated dose of OC was between 7500 and 5000 mg/kg body weight. The subacute toxicity test of OC was examined using 123 mice of both sexes (62 males and 61 females) by feeding a diet mixed with OC at concentrations of 5, 2.5, 1.25, 0.6, and 0.3% for 90 d. All mice tolerated these doses of OC well. The body weight gains of male and female mice were not affected by the treatment. Histopathological examinations showed that hyperplastic changes in the esophagus, forestomach, pancreas, cervix, and endometrium of mice were found in treated and control mice. However, their incidences were not related to the dose of OC. Moreover, only a spontaneous ovarian teratoma was found in an OC‐treated mouse. These results suggest that OC has no acute and subacute toxic effects in mice.