Provided is an adhesive composition for an optical use, including: a first isobutylene-isoprene-based rubber having a weight average molecular weight (Mw) of 100,000 g/mol to 1,000,000 g/mol; and a second isobutylene-isoprene-based rubber having a weight average molecular weight (Mw) of 5,000 g/mol to 100,000 g/mol, in which the first isobutylene-isoprene-based rubber and the second isobutylene-isoprene-based rubber each include a hydroxy group. Further, provided is an adhesive layer including a thermally cured product of the adhesive composition for optical use.