Disclosed is a resin including a structural unit represented by formula (a1-5) and a structural unit represented by formula (I), and a resist composition: wherein Ra8 represents an alkyl group which may have a halogen atom, a hydrogen atom or a halogen atom; Za1 represents a single bond or *—(CH2)h3—CO-L54-; h3 represents an integer of 1 to 4; L51, L52, L53 and L54 each independently represent —O— or —S—; s1 represents an integer of 1 to 3; s1′ represents an integer of 0 to 3; R1 represents a hydrogen atom or a methyl group; A1 represents a single bond or *—CO—O—; R2 represents a halogen atom, a hydroxy group, a haloalkyl group or an alkyl group; mi represents an integer of 1 to 3; and ni represents an integer of 0 to 4, in which mi+ni≤5.