Surface properties such as surface energy and surface charge are important for bone formation on a Ti surface. We investigated the relationship between surface properties (surface energy and surface charge) and initial Ca2+ and PO43- adsorption amounts on titanium surfaces modified with various functional groups (OH, NH2, SH, CH3, CH2=CH, COOH). Surfaces with high surface energy and highly negative zeta potential, such as COOH and OH-modified Ti surfaces, exhibited high Ca2+ adsorption amounts. High surface energy, highly negative zeta potential, and an ideal stoichiometric Ca/P ratio during the initial adsorption of Ca2+ and PO43- led to the precipitation of HAp on COOH-modified Ti surfaces. On the other hand, the adsorption of HAp formed by homogeneous nucleation in the SBF solution occurs on the CH3 and CH2=CH-modified Ti surfaces with low surface energy.