PURPOSE: To improve the color of an alkylpolyglycoside having long-chain alkyl groups as well as to improve its water miscibility without requiring addition of other surfactant or dissolution assistant.

CONSTITUTION: In the production of a surface-active alkylpolyglycoside by converting sugars into glycoside or reconverting the obtained product into glycoside, the reconversion into glycoside is carried out in the presence of a phosphorus-containing mineral acid or its alkali or alkaline earth salt. Thus, the obtd. product has improved water miscibility and an attractive color.