Biocompatible piezoelectric materials are becoming increasingly important for actuators and sensors in medical devices. In this paper, we highlighted on some perovskite-type oxides MgSiO_3, MgTiO_3 CaTiO_3, CaZrO_3 and CaSnO_3 which were discovered through first-principles calculation in our previous studies to fabricate novel lead-free biocompatible piezoelectric materials. In order to verify their biocompatibility, the cytotoxicity of isotopic oxides with the same components was examined as comparing with typical perovskite-type oxides BaTiO_3, LiNbO_3, KNbO_3 and NaNbO_3. The fibroblast (L929) cells were cultured during 7 days and the effect of materials was evaluated by the half maximal inhibitory concentration (IC50). As a result, it was recognized that BaTiO_3, MgSiO_3, CaTiO_3 and CaSnO_3 has the higher biocompatibility. On the other hand, the others has lower biocompatibility. Especially LiNbO_3 and NaNbO_3 shows the strong toxicity.