An adhesive composition which is excellent in adhesion to various hardly adhesive materials such as polyethylene terephthalate, polyethylene, polypropylene, modified polyphenylene ether, polyphenylene sulfide, and a cycloolefin polymer. Further, an adhesive composition containing the following components (A) to (C) may be described Component (A): (Meth) acrylic triblock elastomer having a weight average molecular weight of 80,000 or more, Component (B): (Meth) acrylate monomer having no hydroxyl group and having a phenoxy group, and Component (C): Radical initiator.