Silicate-containing alpha-tricalcium phosphate (α-TCP) ceramics are expected to be useful scaffolds for bone regeneration because α-TCP shows high biodegradability and silicate ions are expected to promote the bone formation. We previously revealed that the porous silicate-containing α-TCP granules provided earlier bone formation and showed lower biodegradability than the porous silicate-free α-TCP granules in vivo. In order to reveal the mechanism of the bone formation promoted by silicate incorporation, the proliferation and differentiation of osteoblast-like cells on the silicate-containing and silicate-free α-TCP ceramics were examined in vitro. The silicate incorporation in α-TCP promoted the differentiation of osteoblast-like cells, and it might be one of the factors to promote bone formation in vivo.