The purpose this study was to investigate the minimization and resource recovery of waste activated sludge by gamma ray irradiation and alkaline treatment. To find the optimal conditions, we examined the effects of TS, SS, SCOD after the gamma ray irradiation and alkaline treatment. SS(suspended solids) was decreased when the gamma ray irradiation dose was increased from 0 kGy to 50 kGy in the waste activated sludge. The efficiency of sludge solubilization could be enhanced by the combined system of alkaline treatment and gamma ray irradiation.