PURPOSE: To obtain a thermosetting bismaleimide resin material which is suitable for the preparation of a fiber-reinforced prepreg using a film impregnation method by incorporating a thermosetting bismaleimide monomer, a specified comonomer, and a specified particulate soluble thermoplastic polyimide.

CONSTITUTION: In the preparation of a thermosetting bismaleimide resin material by incorporating a thermosetting bismaleimide monomer (A), a comonomer (B) selected from an alkenylphenol or an alkenylphenoxy-contg. comonomer and a diamine comonomer, and a soluble, particulate thermoplastic polyimide (C) having a particle size of 2 to about 30 μm in an amt. of 10 to about 60 wt.% based on the total amt. of the components (A), (B), and (C), a major part of a dianhydride residue is accounted for by the formula (X represents a covalent bond, -CR2-, -CO-, -O-CO-, -S-, -SO2- or the like; R represents phenyl or a 6 to 10C cycloalkyl) and 80 wt.% diamine residue corresponds to a residue of toluenediamine and methylenedianiline.