PURPOSE: To provide a thermosetting type polyimide resin composition having excellent mechanical characteristics and adhesiveness while maintaining high heat resistance, comprising a polyfunctional unsaturated imide, a specific thermoplastic resin and a specific plasticizer as essential components.

CONSTITUTION: A thermosetting type polyimide resin composition comprises (A) a polyfunctional unsaturated imide of formula I (D is a divalent carbon-carbon double bond-containing group; R1 is a bi- or polyfunctional organic group; X1 is an integer of two or more), (B) a thermoplastic resin having compatibility with the component A, containing sulfone group, such as a polyether sulfone of formula II (n1 is a positive integer) or a polysulfone of formula III (n2 is a positive integer) and (C) one or more of a polyamine of formula IV (R2 is a di- or polyfunctional organic group; X2 is as shown for X1) and a polycyanic ester compound of formula V (R3 is an aromatic ring-containing di- or polyfunctional organic group; X3 is as shown for X1) as a crosslinking agent for the component A, as essential components. A thermally cured product of the composition forms a structure wherein a phase consisting essentially of the component A and a phase consisting essentially of the component B are separated and these phase are continuously and regularly entangled.