The surface modification of commercially pure titanium by pack cementation treatment using hydroxyapatite (HAp) or tetracalcium phosphate (TTCP) powder was investigated for temperatures ranging from 773 K to 1073 K. An HAp phase was detected on the surface of the titanium substrates after pack cementation treatment at temperatures of 973 K and 1073 K. After treatment using HAp and TTCP powders, a reaction layer with small HAp particles and pores containing small HAp particles, respectively, was observed. Apatite crystallites with a network pattern formed on the pack-cementation-treated titanium substrates after the substrates were immersed in Kokubo solution for 43.2 ks; such rapid apatite formation suggests that pack cementation treatment improves the biocompatibility of titanium.