A method for producing a compound represented by the following formula: where Ar represents a 6-chloro-3-pyridyl group, R 1 represents a C 1-6 alkyl group which may be substituted, and Y represents a hydrogen atom; the method comprising, as shown in the following reaction formula: the steps of: acylating an amino group at position 2 of a compound represented by formula, wherein Y has the same meaning as that described above, by use of an acylating agent represented by R 1 COR 2, where R 1 has the same meaning as that described above, and R 2 represents a trifluoroacetoxy group, a C 1-6 alkyloxy group which may be substituted with a halogen atom or a benzyloxy group whose phenyl group may be substituted with a halogen atom, a methyl group, a cyano group, a nitro group, or a methoxy group, a C 1-6 alkylcarbonyloxy group which may be substituted with a halogen atom, provided that a trifluoroacetoxy group is excluded, or a phenylcarbonyloxy group whose phenyl group may be substituted with a halogen atom, a methyl group, a cyano group, a nitro group, or a methoxy group, a hydroxyl group, or a halogen atom, in the presence or in the absence of a condensation agent, phosphorus pentoxide, sulfuric acid, polyphosphoric acid, thionyl chloride, phosphorus oxychloride, or oxalyl dichloride, to thereby produce a compound represented by formula; and further alkylating a nitrogen atom at position 1 of the compound represented by formula by use of Ar-CH 2 -R 4, where Ar has the same meaning as that described above, and R 4 represents a halogen atom, a C 1-6 alkylsulfoxy group which may be substituted with a halogen atom, or a phenylsulfoxy group which may be substituted with a halogen atom or a methyl group, wherein the acylation is carried out in the absence of a base. acylating an amino group at position 2 of a compound represented by formula, wherein Y has the same meaning as that described above, by use of an acylating agent represented by R 1 COR 2, where R 1 has the same meaning as that described above, and R 2 represents a trifluoroacetoxy group, a C 1-6 alkyloxy group which may be substituted with a halogen atom or a benzyloxy group whose phenyl group may be substituted with a halogen atom, a methyl group, a cyano group, a nitro group, or a methoxy group, a C 1-6 alkylcarbonyloxy group which may be substituted with a halogen atom, provided that a trifluoroacetoxy group is excluded, or a phenylcarbonyloxy group whose phenyl group may be substituted with a halogen atom, a methyl group, a cyano group, a nitro group, or a methoxy group, a hydroxyl group, or a halogen atom, in the presence or in the absence of a condensation agent, phosphorus pentoxide, sulfuric acid, polyphosphoric acid, thionyl chloride, phosphorus oxychloride, or oxalyl dichloride, to thereby produce a compound represented by formula; and further alkylating a nitrogen atom at position 1 of the compound represented by formula by use of Ar-CH 2 -R 4, where Ar has the same meaning as that described above, and R 4 represents a halogen atom, a C 1-6 alkylsulfoxy group which may be substituted with a halogen atom, or a phenylsulfoxy group which may be substituted with a halogen atom or a methyl group, wherein the acylation is carried out in the absence of a base.