To provide a resin composition that contains a lactic acid-based resin and has heat resistance.

This resin composition includes the lactic acid-based resin (A) blended with a fibrous filler (B) coated with a thermoplastic resin having a solubility parameter of which a difference from that of the lactic acid-based resin is 1.0 or more but 2.5 or less, wherein a rate of the fibrous filler (B) in the mixture of the lactic acid-based resin (A) and the fibrous filler (B) is 10 mass% or more but 60 mass% or less; and the relative degree of crystallinity of c(A) of the lactic acid-based resin (A), the crystallization heat quantity Hc(A) of the lactic acid-based resin (A), and the crystal melting heat quantity Hm(A) of the lactic acid-based resin (A) meet the following relationship: c(A)={Hm(A)-Hc(A)}/Hm(A)0.90.