Commercially pure titanium (c.p.Ti) is capable of inducing the formation of a carbonated apatite onto its surface in a simulated body fluid (SBF) comprised of calcium ions, phosphate ions, and other inorganic species present in the body fluid. In addition to the incorporation of carbonate ions, such formed apatite has other important characteristics of the bone mineral phase, such as a small crystal size and ionic substitution by Mg2+ and Cl-. Thus, we call this apatite a quasi-biological apatite. The formation of the quasi-biological apatite is proposed to be related to TiOH groups that develop on the titanium surface through interaction with the SBF. The results suggest that titanium implants may be activated such that they can form a strong bond with bone tissue through the in vivo formation of apatite. Since the solution can reach any open space, the process discussed in this study is very suitable for coating porous titanium implants with a quasi-biological apatite film.