To produce a new carotenoid glycoside, comprising astaxanthin diglucoside and adonixanthin 3'-glucoside, having a high polarity and a high solubility in water and useful as a color tone improving agent for cultured fishes and shellfishes, a food additive, etc.

This new carotenoid glycoside comprises astaxanthin diglucoside represented by a chemical structural formula of formula I and adonixanthin 3'-glucoside represented by a chemical structural formula of formula II, has a high polarity and a high solubility in water and is useful as a color tone improving agent for cultured fishes and shellfishes, a food additive, etc. The compounds are obtained by transferring all or a part of carotenoid biosynthesis genes crtE, crtB, crtI, crtY, crtZ, crtX and crtW into a microorganism, making the seven genes present therein so as to enable the expression, culturing the resultant transformed microorganism in a culture medium and collecting the prepared product from the resultant cultured product.