Type I collagen was coated onto the modified surfaces of hydroxyapatite (HAp) sintered body. The interfacial interaction between collagen and HAp in a nano-region was controlled by depositing the organosilane of n-octadecyltrimethoxysilane (ODS: -CH3) or aminopropyltriethoxysilane (APTS: -NH2) with a chemical vapor deposition method. The surfaces were elaborated by X-ray photoelectron spectroscopy, zeta-potential, and contact angle measurements; the Si and/or N peaks were detected, and the contact angles and surface energies were apparently different on the modified surfaces. The morphologies of collagen adsorbed on the surfaces of HAp and HAp deposited with APTS were similar, however that of the surface with ODS was apparently different, due to the hydrophobic interaction between the organic head group of -CH3 and residual groups of collagen.