A polypropylene-based resin composition of drastically improved
dimensional stability realized by incorporating a polypropylene resin of
specific structure with an inorganic filler of specific particle size,
carbon fibers of specific fiber diameter and length, and, as required, an
ethylene- and/or styrene-based elastomer. Another polypropylene-based
resin composition of well-balanced properties of rigidity,
heat-resistance, impact resistance and lightness even essentially in the
absence of inorganic filler, realized by compositing a propylene/ethylene
block copolymer of specific structure and well-balanced mechanical
properties with an ethylene- and/or styrene-based elastomer, and carbon
fibers of specific structure.