BPMC (2-Sec-butylphenyl N-methylcarbamate) was treated at the level of 100mg/kg/day in oral administration for 12th days in rat. It was investigated not only that the hematogram and the serological parameters, but also the content of cytochrome P-450, the activity of TBA, glucose-6-phosphatase, cholinesterase and carboxylesterase in rat. The results were as follows: The hematogram was not found any alteration but the value of AST, ALT, LDH and the content of glucose in serum were significantly increased compare with that of control group. The content of cytochrome P-450 in liver was increased significantly on the contrary cytochrome P-450 in kideny and NADPH-cytochrome c reductase in liver and Kidney were not significantly increased. After the final 12th day, the value of TBA and the activity of glucose-6-phosphatase appeared to the tendency of increasement in the liver. The activity of cholinesterase and carboxylesterase both in serum and liver were decreased. Especially the activity of cholinesterase was more significantly decreased. It was conclusion that the function of this insectivide should be due th the inhibition of cholinesterase activity.