Production and purification methods for efinaconazole are provided by which high-purity efinaconazole can be obtained in high yield through a simple procedure using a specific impurity as an index, the methods being suitable for industrial scale. The production method for efinaconazole is characterized by comprising step A, in which a toluene solution comprising compound (II), compound (III), an inorganic base, and toluene is formed, the amount of the toluene in volume (L) being 2-5 times the mass (Kg) of the compound (II), step B, in which the toluene solution is reacted with heating, and step C, in which the liquid reaction mixture obtained in step B is washed to obtain a crude toluene solution of efinaconazole which has a residual 4-MP content of 5 wt% or less with respect to the efinaconazole.
