A polyimide resin composed of a repeating unit represented by the following formula (1): or composed of the repeating unit represented by the formula (1) and at least one repeating unit represented by the following formula (2): wherein X is the same as defined in the specification, exhibits a good thermoplastic property, a high solubility in solvents and a good heat resistance as well as a low water absorption and an excellent adhesion property. The polyimide resin is useful as the material for the adhesive layer of a metal-clad laminate which is composed of an insulating substrate, a metal layer and an adhesive layer disposed between the insulating substrate and the metal layer.