A release agent for plastic, comprising the following components to and having an average particle size of 200 nm or less, wherein the average particle size is measured in accordance with the description: 100 parts by mass of an organopolysiloxane represented by the following general formula and having a viscosity at 25°C of 100 to 100,000 mm 2 /s, measured in accordance with the description wherein R 1 is identical to or different from one another and represents a hydroxy group, a hydrogen atom, a linear, unsubstituted alkyl group having 1 to 32 carbon atoms, or a phenyl group, L represents an integer of 60 to 1500, and octamethyl cyclotetrasiloxane, decamethyl cyclopentasiloxane, and dodecamethyl cyclohexasiloxane are each contained in an amount of less than 3% in the organopolysiloxane; 0.1 to 15.0 parts by mass of one or more anionic surfactants selected from alkyl sulfonate salts, alkylbenzene sulfonate salts, alpha olefin sulfonate salts, polyoxyethylene alkyl ether sulfate salts, alkyl ether sulfate salts, polyoxyethylene alkyl ether acetate salts, alkyl acetate salts, alkyl phosphate salts, polyoxyethylene alkyl ether phosphate salts, alkyl sulfosuccinate salts, polyoxyethylene alkyl ether sulfosuccinate salts, methyl taurate, alaninate, and salts thereof; 1.0 to 30.0 parts by mass of a polyoxyethylene alkyl ether represented by the following general formula, C m H 2m+1 (OCH 2 CH 2) n OH wherein "m" represents an integer of 12 to 20, and "n" represents an integer of 4 to 50, provided that when "m" is an integer of 12 to 15, "n" is 8 to 50, and when "m" is 16 to 20, "n" is 4 to 50; 0.5 to 15.0 parts by mass of a polyoxyethylene sorbitan fatty acid ester represented by the following general formula, wherein R 2 represents an alkyl group having 12 to 18 carbon atoms, and a sum of a+b+c is 20; and 50 to 100,000 parts by mass of water. 100 parts by mass of an organopolysiloxane represented by the following general formula and having a viscosity at 25°C of 100 to 100,000 mm 2 /s, measured in accordance with the description wherein R 1 is identical to or different from one another and represents a hydroxy group, a hydrogen atom, a linear, unsubstituted alkyl group having 1 to 32 carbon atoms, or a phenyl group, L represents an integer of 60 to 1500, and octamethyl cyclotetrasiloxane, decamethyl cyclopentasiloxane, and dodecamethyl cyclohexasiloxane are each contained in an amount of less than 3% in the organopolysiloxane; L represents an integer of 60 to 1500, and octamethyl cyclotetrasiloxane, decamethyl cyclopentasiloxane, and dodecamethyl cyclohexasiloxane are each contained in an amount of less than 3% in the organopolysiloxane; 0.1 to 15.0 parts by mass of one or more anionic surfactants selected from alkyl sulfonate salts, alkylbenzene sulfonate salts, alpha olefin sulfonate salts, polyoxyethylene alkyl ether sulfate salts, alkyl ether sulfate salts, polyoxyethylene alkyl ether acetate salts, alkyl acetate salts, alkyl phosphate salts, polyoxyethylene alkyl ether phosphate salts, alkyl sulfosuccinate salts, polyoxyethylene alkyl ether sulfosuccinate salts, methyl taurate, alaninate, and salts thereof; 1.0 to 30.0 parts by mass of a polyoxyethylene alkyl ether represented by the following general formula, C m H 2m+1 (OCH 2 CH 2) n OH wherein "m" represents an integer of 12 to 20, and "n" represents an integer of 4 to 50, provided that when "m" is an integer of 12 to 15, "n" is 8 to 50, and when "m" is 16 to 20, "n" is 4 to 50; 0.5 to 15.0 parts by mass of a polyoxyethylene sorbitan fatty acid ester represented by the following general formula, wherein R 2 represents an alkyl group having 12 to 18 carbon atoms, and a sum of a+b+c is 20; and 50 to 100,000 parts by mass of water.