To provide a refrigerator oil for a refrigerant, used together with a hydrocarbon refrigerant containing a hydrogen-containing flon containing no chlorine, or a hydrocarbon refrigerant containing no halogen atoms, exhibiting a small greenhouse gas effect, and low in viscosity and excellent in safety and stability.

A refrigerator oil contains 25 to 40 mass% of a monoester of a 8C aliphatic monoalcohol and a 8C monovalent fatty acid, and 60 to 75 mass% of at least one polyol ester of 2-ethylhexanoic acid and/or 3,5,5-trimethylhexanoic acid and a 5-10C neopentylpolyol.