The purpose of the invention is to provide a method for producing a compound of formula (1) with high yield through a ring opening addition reaction of an amine with epoxytriazole under mild conditions without using a large excess amount of 4 methylenepiperidine. The method is a method for producing (2R 3R) 2 (2 4 difluorophenyl) 3 (4 methylenepiperidin 1 yl) 1 (1H 1 2 4 triazol 1 yl) butan 2 ol or an acid addition salt thereof and comprises reacting (2R 3S) 2 (2 4 difluorophenyl) 3 methyl 2 [(1H 1 2 4 triazol 1 yl)methyl]oxirane with an acid addition salt of 4 methylenepiperidine in a reaction solvent in the presence of a hydroxide of an alkali metal or an alkaline earth metal selected from the group consisting of lithium sodium calcium and strontium or a hydrate thereof.
