The present invention relates to a method for analyzing residual agricultural chemicals which comprises the steps of acting a reduced glutathione as a reactive substrate and a glutathione transferase serving as a catalyst for the reaction on a carbofuran derivative or a methomyl derivative as a carbamate type agricultural chemical of a new series to thus derivatize the agricultural chemical into a substance having a high choline esterase-inhibitory activity; reacting the substances formed through the derivatization reaction with a choline esterase; and then detecting the presence of the agricultural chemical as the new series of carbamate type one included in a sample to be examined on the basis of the changes in the choline esterase activity thus detected. The method of the present invention may serve as a powerful tool for the detection of the residual agricultural chemicals in grains such as rice and the detection of the content of agricultural chemicals remaining in agricultural products such as vegetables and fruits.