PURPOSE: To provide the titled compsn. having excellent heat resistance, rigidity, dimensional stability, etc., consisting of a polyolefin resin, a specified resin and a fibrous or flaky inorg. filler.

CONSTITUTION: 3W80pts.wt. inorg. filler (A) in the form of a fiber having a diameter of 30μm or below or a flak having an aspect ratio of 30 or above, which has a network structure formed by coating both edges or part thereof with 20W150pts.wt. resin (e.g. polyethylene terephthalate) with is not uniformly compatible with component B, forms a dispersion with component B and has a crystalline m.p. of 120°C or above or a glass transition point (in non-crystalline form) of 120°C or above, is blended with 100pts.wt. polyolefin resin (B) (e.g. crystalline PP) having a number-average MW of 30,000 or above, a crystalline m.p. of 100°C or above, an MFR os 0.005W100g/10min and an n-heptane- insolubles content of 70wt% or above.