Twelve residual pesticides which is applied mainly on the fruits and vegetables cultivation were tested for mutagenic activity using Salmonella typhimurium. The results were as follows. 1) The pesticides tested - Thalonil, Monopho, Tedion, Danoton, Ometon, Prosing, EPN, Phentoate, Parathion, 8appiran and Captan-, except Dicofol, showed mutagenic activity. Especially, the pesticides which activated with 8-9 mixture gave strong mutagenic activity. 2) With Salmonella typhimurium TA100, the pesticides Monopho, Parathion and Sappiran showed mutagenic activity at $0.5{\mu}g/plate;\;Ometon,\;0.01\; t.tl/plate;Thalonil,\;0.20{\mu}g/plate;\;Prosing,\; 0.20{\mu}l/plate;$ Tedion, Danoton and Phentoate, $1.0\;{\mu}l/plate;\;and\;Captan,\;1.0\;{\mu}g/plate.$ 3) With Salmonella typhimurium TA98, the pesticide Sappiran showed mutagenic activity at $0.02\;{\mu}g/plate;\;Thalonil,\;0.05\;{\mu}g/plate;\;EPN,\;0.05\;{\mu}/plate;\; Phentoate,\;0.10\; {\mu}l/plate;\;Danoton,\;0.50\;{\mu}l/plate;$ Prosing, $ 0.50\;{\mu}g/plate;\;and\;Tedion\;and\;Monopho,\;1.0\;{\mu}l/plate.$ 4) With Salmonella typhimurium TA1535, The pesticides Captan and Danoton showed mutagenic activity at $0.10\;{\mu}g/plate\;and\;0.20\;{\mu}g/plate,\;respectively.$ 5) With Salmonella typhimurium TA1538, The pestides Phentoate showed mutagenic activity at $0.05\;{\mu}l/plate;\;Monopho,\;0.10\;{\mu}l/plate;\;Thalonil,\;0.20 {\mu}g/plate;\;and\;Tedion\;and\;EPN,\;1.0\;{\mu}l/plate.$ 6) The pesticides which commonly showed high mutagenic activity were Thalonil, Phentoate, Parathion and Sappiran. The pesticides Ometon and EPN showed mutagenic activity at only TA100 and TA98, respectively.