Silicon-doped calcium carbonate / poly (lactic acid) composites (Si-CCPC) were estimated in cellular biocompatibility with culture tests using osteoblast-like cells (MC3T3-E1) and mesenchymal stem cells (MSC). The cellular biocompatibility of Si-CCPC was enhanced by coating with bone-like hydroxycarbonate apatite (b-HA) formed by simulated body fluid immersion. The b-HA was formed on Si-CCPC after 3-days of immersion and closely bonded with Si-CCPC. Numerous MC3T3-E1 and MSC showed good adhesion on the b-HA with extending their lamellipodia. The number of adhering MC3T3-E1 on Si-CCPC coated with the b-HA was higher than that on Si-CCPC. The b-HA has excellent biocompatibility and silicon is regarded to stimulate osteoblast and bone formation in vivo and vitro. The b-HA containing silicon on Si-CCPCis expected to enhance the cellular adheresion, proliferation and differentiation.