PURPOSE: To enable a polyimide film to be bonded with a high heat resistance and an excellent peeling resistance by using an adhesive comprising a thermosetting oxazene resin having a 1-oxa-3-aztetralin group.

CONSTITUTION: A polyimide film is bonded by using a thermosetting oxazene resin having at least one 1-oxa-3-azatetralin group in the molecule as an adhesive. A combination of the oxazene resin with a curable epoxy resin may be used as the adhesive; in this case, the molar ratio of epoxy group to 1-oxa-3- azatetralin group is pref. 0.8-1.5. Thus, a polyimide film can be bonded with a high heat resistance and an excellent peeling resistance. This method is suitable for bonding a polyimide film to the same kind of a film or to other substrates (esp. a metal foil).