A polyphenylene sulfide resin composition which comprises 100 parts by weight of a polyphenylene sulfide resin (A) and, compounded therewith, 1 to 100 parts by weight of glass fibers (B) having a single-fiber diameter of 12 .mu.m or lager and has a crystallization temperature during cooling of 205.degree. C. or lower. Also provided is a polyphenylene sulfide resin composition which comprises 100 parts by weight of a polyphenylene sulfide resin (A) and, compounded therewith, 1 to 100 parts by weight of glass fibers (B) having a single-fiber diameter of 10 to 12 .mu.m, excluding 12 .mu.m, has a crystallization temperature during cooling of 205.degree. C. or lower and a chloroform-extractable content of 0.5 wt. % or lower, and gives a 2 mm-thick molded product which has a transmittance of 15% or higher for laser beam having a wavelength of 940 nm and a heat distortion temperature of 230.degree. C. or higher under a load of 1.82 MPa.