A novel material, namely, TiO2-HDPE (TiO2/high density polyethylene) composite was developed by our research group. Its mechanical properties are similar to those of the human cortical bone; hence, we examined the possibility of using it as a bone substitute. We prepared two groups of TiO2-HDPE; one was subjected to ultraviolet irradiation for 0.1 h and the other for 9 h. In bone bonding ability test, the former indicated a lower ability than the latter, which showed approximately 7 to 8 N of failure load. The bone bonding ability of the latter group alone is not sufficient for clinical application; on the other hand, the biocompatibility test was carried out. In the biocompatibility test, the group that was irradiated for 9 h revealed neither a major inflammatory response nor formation of neoplasm. We have to further examine alternate types of polyethylene or TiO2 particles in order to improve the bone bonding ability.