The present paper deals with the changes in the Ca⁺⁺-ATPase activity ofmyofibrillar protiens from minced fish meat of grass carp (Ctenopharyngodon idellus)in refrigeration. The effect of several kinds of factor on Ca⁺⁺--ATPase activity wereexamined. The Ca⁺⁺-ATPase activity was considered to be useful in evaluating thequality of minced fish meat in the refrigerating process.