To provide a method for quickly, simply and easily judging the elevation of a mixed functional oxidase activity in the insect by using a single individual body of the insect.

This method for inspecting the insecticide resistance is provided by comprising a process of homogenizing by crushing the single individual body of the insect in an acidic buffer in preferably a small-sized tube such as an Eppendorf tube with a pestle for crushing, a process of adding tetramethylbenzidine solution buffered with the acidic buffer as a substrate, a process of adding hydrogen peroxide as an oxidizing agent and a process of judging the elevation of the mixed functional oxidase activity by evaluating the coloration intensity of a blue color. The test kit used in the above method includes in a plurality of containers for housing separately each of the acidic buffer (preferably pH 4 buffer), tetramethylbenzidine, a solvent for tetramethylbenzidine (preferably methanol) and hydrogen peroxide.