To obtain an adhesive composition excellent in stability when heated to melt by compounding a cationic polymerizable compound and a specified amount of an aromatic sulfonium salt containing phosphorus hexafluoride as a counter anion, as a cationic polymerization initiator.

An adhesive composition comprises 100 pts.wt. of a cationic polymerizable compound or 100 pts.wt. of the total of the cationic polymerizable compound and a polycarbonate and 0.01-10 pts.wt. of a cationic polymerization initiator such as an aromatic sulfonium salt containing phosphorus hexafluoride as a counter anion, or the like, and further contains a polyhydroxyl compound such as a polyoxyalkylene glycol, a thermoplastic resin such as a polyolefinic resin and the like, an adhesion improving agent such as vinyltrichlorosilane or the like, a filler, a softening agent and the like. As the cationic polymerizable compound is employed a bisphenol type epoxy resin, a novolak type epoxy resin or the like having a softening temperature of 40-200°C and a wt. average mol.wt. of 50-100,000. As the polycarbonate is employed an aliphatic hydroxyl group-containing polycarbonate or the like.