PURPOSE: To provide the titled composition giving a molded article having excellent bending strength at high temperature and high heat resistance, by compounding a thermosetting resin with specific amounts of a phosphorus oxyacid salt compound and a filler.

CONSTITUTION: The objective composition is prepared by mixing and dispersing (A) a thermosetting resin (e.g. phenolic resin) with (B) 5W250wt% (based on the thermosetting resin) of a phosphorus oxyacid salt compound of formula MOm/2. nP2O5 (M is metal including Si; m is atomic valence of M; n is 0.1W0.7) (e.g. silicon polyphosphate), (C) 15W200wt% of a filler (e.g. silica) and if necessary, (D) an internal mold release agent (e.g. zinc stearate). The sum of the components (B) and (C) is 20W250wt%.