Hydroxyapatite (HAP) possesses extremely high ability of bioactivity and ion exchange. In this study, hydroxyapatite containing amorphous silica was prepared by heat-treatment in air atmosphere for the mixture of hydroxyapatite and amorphous silica powders in order to develop the high performance modified hydroxyapatites. Their microstructures of the samples prepared by heat-treatment at various temperatures were examined by scanning electron microscopy (SEM) and their characterizations were evaluated with X-ray diffraction (XRD) and fourier transform infrared spectrophotometry (FT-IR) and so on. XRD results indicated that the incorporation of Si ion as a SiO44- into PO43- site arose the increase of lattice constants for hydroxyapatite structure. These results suggested that SiO44 was substituted to PO43- site in HAP structures, leading to the successful synthesis of Si-incorporated hydroxyapatite.