The present invention provides a refrigerating machine oil comprising: a lubricating base oil; and 40 mass % or less of a polymer, based on a total amount of the refrigerating machine oil, the polymer having a structural unit represented by the following formula (I) and a weight average molecular weight of from 500 to 100000. [In formula (I), Ra, Rb and Rc each independently represents a hydrogen atom or a hydrocarbon group, and Rd represents an oxygen-containing organic group or a C1-18 hydrocarbon group.]