There is provided a crystalline polylactic acid resin composition comprising 95 to 99.97 parts by mass of a polylactic acid resin (A) having a D-isomer content of not greater than 0.6 mol % or not less than 99.4 mol %, and 0.03 to 5 parts by mass of a crystal nucleus agent (B). There is also provided a crystalline polylactic acid resin composition prepared by melt-kneading 100 parts by mass of a polylactic acid resin (A) having a D-isomer content of not greater than 0.6 mol % or not less than 99.4 mol %, 0.01 to 20 parts by mass of a (meth)acrylate compound (C), and 0.02 to 20 parts by mass of a peroxide (D).