The present invention relates to a novel refrigeration oil comprising any one of the following three: (A) a polyol ester (POE) obtained by reacting one or more polyol(s) with one or more C 4-10 straight or branched chain fatty acid(s) and one or more C 5-10 fatty acid(s) having a specific structure, (B) a mixture of above (A) polyol ester and another polyol ester obtained by reacting one or more polyol(s) with one or more C 4-10 straight or branched chain fatty acid(s) and one or more C 5-10 fatty acid(s) having a specific structure, and (C) a mixture of one or both of the aforesaid (A) polyol ester and (B) polyol ester with a polyol ester obtained by reacting a polyol with the other fatty acid than the aforesaid C 5-10 fatty acid(s) having a specific structure.
