A mixed composition for a refrigerator, comprising: a refrigerant containing at least one unsaturated fluorinated hydrocarbon compound selected from compounds represented by the following molecular formula: C p F r H s wherein p represents an integer of from 2 to 6; r represents an integer of from 1 to 11; and s represents an integer of from 1 to 11, provided that the compound has one or more carbon-carbon unsaturated bond in a molecule, and a refrigerator lubricating oil containing, as a major component, a polyoxyalkylene glycol compound represented by the following general formula, and containing a phenothiazine compound in an amount of 1.0% by mass or more based on the total amount of the refrigerator lubricating oil: R 1 -[(OR 2) m -OR 3] n wherein R 1 is selected from a hydrogen atom, an alkyl group having a number of carbon atoms of from 1 to 10, an acyl group having a number of carbon atoms of from 2 to 10, an aliphatic hydrocarbon group having a number of carbon atoms of from 1 to 10 and having from 2 to 6 bonding sites, and a substituent having a number of carbon atoms of from 3 to 15 and containing a heterocyclic ring which has oxygen and/or sulfur as a heteroatom; R 2 represents an alkylene group having a number of carbon atoms of from 2 to 4; R 3 represents a hydrogen atom, an alkyl group having a number of carbon atoms of from 1 to 10, or an acyl group having a number of carbon atoms of from 2 to 10; n represents an integer of from 1 to 6; and m represents a number such that an average value of m × n is from 6 to 80, wherein the phenothiazine compound is at least one selected from methoxyphenothiazine, 2-(trifluoromethyl)phenothiazine, 2-acetylphenothiazine, 1-azaphenothiazine, and a phenothiazine-styrene derivative. a refrigerant containing at least one unsaturated fluorinated hydrocarbon compound selected from compounds represented by the following molecular formula: C p F r H s wherein p represents an integer of from 2 to 6; r represents an integer of from 1 to 11; and s represents an integer of from 1 to 11, provided that the compound has one or more carbon-carbon unsaturated bond in a molecule, and a refrigerator lubricating oil containing, as a major component, a polyoxyalkylene glycol compound represented by the following general formula, and containing a phenothiazine compound in an amount of 1.0% by mass or more based on the total amount of the refrigerator lubricating oil: R 1 -[(OR 2) m -OR 3] n wherein R 1 is selected from a hydrogen atom, an alkyl group having a number of carbon atoms of from 1 to 10, an acyl group having a number of carbon atoms of from 2 to 10, an aliphatic hydrocarbon group having a number of carbon atoms of from 1 to 10 and having from 2 to 6 bonding sites, and a substituent having a number of carbon atoms of from 3 to 15 and containing a heterocyclic ring which has oxygen and/or sulfur as a heteroatom; R 2 represents an alkylene group having a number of carbon atoms of from 2 to 4; R 3 represents a hydrogen atom, an alkyl group having a number of carbon atoms of from 1 to 10, or an acyl group having a number of carbon atoms of from 2 to 10; n represents an integer of from 1 to 6; and m represents a number such that an average value of m × n is from 6 to 80, wherein the phenothiazine compound is at least one selected from methoxyphenothiazine, 2-(trifluoromethyl)phenothiazine, 2-acetylphenothiazine, 1-azaphenothiazine, and a phenothiazine-styrene derivative.