To obtain the subject compound useful as an industrial chemical, a medicine and a raw material for cosmetic on an industrial scale efficiently by subjecting a specific tetrahydropyran derivative to solvolysis in the presence of a base in an organic solvent, then neutralizing the resultant substance with an acid and crystallizing the neutralized substance.

A compound of formula I (R1 to R4 are each H, OH or the like; R5 is H, a 1-4C alkyl or the like with the proviso that one or more of R1 to R4 are each a 1-4C alkylcarbonyloxy) (e.g. 4-acetyloxyphenyl-2,3,4,6-tetra-O- acetyl-β-D-glucopyranoside, etc.), is subjected to solvolysis in the presence of a base such as sodium methylate, etc., in an organic solvent such as methanol, etc., then neutralized with an acid such as acetic acid, etc., crystallized to give the objective compound of formula II (Z1 to Z5 are each as shown for R1 to R5 with the proviso that a condition in which the 1-4C alkylcarbonyloxy of formula I is converted into OH is satisfied) (e.g. arbutin, etc.).