To supply a derivative having a 2-acyliminopyridine structure and being represented by the following formula (I) in an amount required as a pest control agent stably and at a low cost, provided is a method comprising the steps of: acylating an amino group at position 2 of a compound represented by formula (A) by use of an acylating agent, to thereby produce a compound represented by formula (B)； and further alkylating a nitrogen atom at position 1 of the compound represented by formula (B):[where Ar represents a phenyl group or a 5-to 6-membered heterocycle, R1 represents a C1-6 alkyl group, and Y represents a hydrogen atom； a halogen atom； a hydroxyl group； a C1-6 alkyl group which may be substituted with a halogen atom； a C1-6 alkyloxy group which may be substituted with a halogen atom； a cyano group； a formyl group； or a nitro group].
