To obtain a resin composition that can increase the mechanical strength of molding products, reduce the deterioration in its physical properties after a thermo-hygrostat test and is useful as parts for vehicles and electric appliances and as a building material by using an inorganic filler, a thermoplastic resin and a specific phosphorus compound.

This resin composition contains (A) a phosphorus compound bearing a double bond in the molecule, for example, 4-acryloxybutyl dihydrogen phosphate, (B) an inorganic filler with an aspect ratio of 5-200 and (C) a thermoplastic resin with a solubility parameter of 9.0-12.0 such as polyester, polycarbonate, ABS resin or poly(phenylene ether).