An organopolysiloxane that can suppress swelling of a container due to a hydrogen gas derived from Si—H groups and occurrence of an offensive odor derived from aliphatic unsaturated groups, and that is excellent in emulsification stability and has good cosmetic durability, and a cosmetic containing the same. The organopolysiloxane being represented by the following average formula (1): wherein, R1 represents a group selected from an alkyl group having 1 to 30 carbon atoms, etc., R2 represents a divalent organic group having 2 to 15 carbon atoms, R3 represents any of a hydrogen atom and an alkyl group having 1 to 30 carbon atoms, R4s each independently represent a group selected from an alkyl group having 2 to 30 carbon atoms and another organopolysiloxane, “a” is 1 to 500, “b” is 1 to 10, and “c” is 1 to 10.