Refrigerating machine oil

1. A refrigerating machine oil comprising:

a lubricating base oil consisting of at least one oxygen-containing oil selected from an ester and an ether; and

1 to 40 mass % 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;

wherein in formula (I), R a , R b and R c each independently represents a hydrogen atom or a hydrocarbon group, and R d represents an oxygen-containing organic group or a C 1-18 hydrocarbon group.

2. The refrigerating machine oil according to claim 1 , wherein the ester comprises an ester of polyhydric alcohol and carboxylic acid.

3. The refrigerating machine oil according to claim 1 , wherein the refrigerating machine oil is used together with at least one refrigerant selected from a saturated fluorohydrocarbon refrigerant, an unsaturated fluorohydrocarbon refrigerant, a hydrocarbon refrigerant and a natural refrigerant.

4. A refrigerating machine, comprising the refrigerating machine oil according to claim 1 .

5. A working fluid composition for a refrigerating machine, comprising:

a refrigerant; and

the refrigerating machine oil according to claim 1 .

6. The working fluid composition for a refrigerating machine according to claim 5 , wherein the refrigerant is at least one refrigerant selected from a saturated fluorohydrocarbon refrigerant, an unsaturated fluorohydrocarbon refrigerant, a hydrocarbon refrigerant and a natural refrigerant.

7. A refrigerating machine, comprising the working fluid composition for a refrigerating machine according to claim 5 .