PURPOSE: To purify the titled compound useful as an insecticide, etc., having high insecticidal activity and low toxicity to warm-blooded animals, by bringing an alkali aqueous solution, etc. into contact with a solution of an unpurified aminosulfenylcarbamte derivative in a water-insoluble organic solvent.

CONSTITUTION: An alkali aqueous solution or an alkali mixed solution of water and a water-soluble organic solvent is brought into contact with a solution of an unpurified aminosulfenylcarbamate derivative in a water-insoluble organic solvent, to give the desired purified compound shown by the formula I [Ar is group shown by the formula II or formula III; R1 and R2 are 1W8C alkyl, 3W6C cycloalkyl, (substituted)phenyl, or group shown by the formula -X-COOR3 (X is alkylene; R3 is 1W8C alkyl, etc.), group shown by the formula -Y-CN(Y is alkylene), or R1 and R2 are linked to form 5- W6-membered ring which may contain N, S, or O].