ADHESIVE COMPOSITION AND ADHESIVE SHEET

PROBLEM TO BE SOLVED: To provide adhesive compositions and adhesive sheets which have strong adhesion when not irradiated with active energy rays and can remarkably reduce the adhesion after irradiation with active energy rays and, simultaneously, can retain these performance characteristics after long-term storage. SOLUTION: An adhesive composition comprises a copolymer having, as the constituting monomer units, (A) 10-80 wt.% compound having both an ethylenically unsaturated group and a cyclic imide group represented by the formula, wherein R1 and R2 are each independently a hydrogen atom or a 4>=C alkyl group or R1 and R2 are unsaturated or saturated hydrocarbon groups which jointly form a 5- or 6-membered ring, and (B) 90-20 wt.% ethylenically unsaturated group-containing monomer excluding component (A), and the peel strength is reduced after the composition has been irradiated with active energy rays. An adhesive sheet has an adhesive layer formed of this composition.