Withdrawal time of erythromycin in the cultured black rockfish (Sebastes schlegeli) was investigated to provide regulatory authority and fishery industry with full information needed to secure food safety of the fish treated with erythromycin. Medication was carried out using the experimental diet containing erythromycin of which concentration was 200 mg/kg diet and its daily dose was about 40 mg/kg body weight. The withdrawal time needed to reduce antibiotic contents around 10.0 mg/kg accumulated during 9 days medication below 0.2 mg/kg was identified about 10 days. The antibiotic with 13.7 mg/kg of fish on the $9^{th}$ days of medication was completely depleted after 30 days from stop of medication.