Disclosed is a monomer containing an N-acylcarbamoyl group and a lactone skeleton. The monomer is exemplified by Formula (1): where Ra is selected typically from hydrogen and C1-C6 alkyl; R1 is, independently in each occurrence, selected typically from halogen and optionally halogenated C1-C6 alkyl; “A” is selected from C1-C6 alkylene, oxygen, sulfur, and non-bond; m represents an integer of 0 to 8; X represents, independently in each occurrence, specific N-acylcarbamoyl; n represents an integer of 1 to 9; and Y represents a C1-C6 divalent organic group.