PURPOSE: To provide a refining method which can effectively deodorize and bleach a fish oil by bringing a fish oil into contact with a resin having a high water absorption capacity.

CONSTITUTION: A method for refining a fish oil, comprising bringing a fish oil into contact with a resin having a high water absorption capacity. The resin having a high water absorption capacity is pref. either a cross-linked product based on a salt of acrylic acid or a modification of a cross-linked polyvinyl alcohol. Still pref., the fish oil is subjected to steam distillation and then brought into contact with the resin having a high water absorption capacity. Still further pref., the fish oil is brought into contact with the resin having a high water absorption capacity under a reduced pressure of 300mmHg or below in terms of degree of vacuum. The cross-linked product based on a salt of acrylic acid may be prepd., e.g. by adding a cross-linking agent, such as a polyfunctional vinyl monomer, to a mixture of (meth)acrylic acid and a water- soluble salt of (meth)acrylic acid and conducting polymn.