Refrigerator oil and refrigerator working fluid composition

A refrigerating machine oil comprising:

• a base oil comprising an ester and comprising no ether;
• a dithiophosphoric acid ester;
• and
• an amine salt of acidic phosphoric acid ester;
• wherein the base oil comprises at least one selected from the group consisting of a polyol ester and a complex ester,
• the polyol ester comprises a polyol ester of pentaerythritol and a fatty acid having 4 to 9 carbon atoms,
• the complex ester is an ester synthesized from
• neopentyl glycol,
• at least one selected from the group consisting of a dihydric alcohol having 2 to 10 carbon atoms other than neopentyl glycol,
• at least one selected from the group consisting of a polybasic acid having 6 to 12 carbon atoms, and
• at least one selected from the group consisting of a monohydric alcohol having 4 to 18 carbon atoms;
• a content of the base oil is 90% by mass or more based on a total amount of the refrigerating machine oil,
• the dithiophosphoric acid ester is a compound represented by the following formula (A-3):
• wherein R1 and R2 each independently represent an alkyl group having 3 or more and 9 or less carbon atoms, and R6 and R7 each independently represent a hydrogen atom or an alkyl group having 1 or more and 4 or less carbon atoms,
• a content of the dithiophosphoric acid ester is 0.01% by mass or more and 0.1% by mass or less based on a total amount of the refrigerating machine oil,
• the amine salt of acidic phosphoric acid ester is a salt of an acidic phosphoric acid ester represented by the following formula (B-1) and an amine represented by the following formula (B-2):
• wherein R11 represents an alkyl or alkenyl group having 4 or more and 18 or less carbon atoms, n represents 1 or 2, R12, R13 and R14 each independently represent a hydrogen atom or an alkyl group having 5 or more and 16 or less carbon atoms, and at least one of R12, R13 and R14 represents the alkyl group having 5 or more and 16 or less carbon atoms,
• a content of the amine salt of acidic phosphoric acid ester is 0.01% by mass or more and 0.1% by mass or less based on a total amount of the refrigerating machine oil, and
• wherein a mass ratio of the content of the dithiophosphoric acid ester to the total content of the dithiophosphoric acid ester and the amine salt of acidic phosphoric acid ester is 0.5 or less and wherein the refrigerating machine oil is used with a refrigerant.