A refrigerator oil composition contains base oil and polyalkylene glycol (PAG) block copolymer. The PAG block polymer is represented by the following formula (1). R1[(OR2)m(OE)nOR3]1  (1) In the formula: R1 represents a hydrocarbon residue having 1 to 10 carbon atoms; R2 represents an alkenyl group having 3 to 6 carbon atoms; E represents an ethylene group; R3 represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms; m and n each represent a positive integer, a ratio of m to n (m/n) being 99/1 to 50/50; and l represents an integer in a range of 1 to 100.