In previous studies, Zr gained apatite-forming ability by various methods; however, it took more than 7 days in simulated body fluid (SBF) to gain apatite-forming ability. In this study, the authors developed the method to achieve apatite-forming ability in Zr alloy within 1 day in SBF by a combination with apatite nuclei that promote apatite formation in SBF. First, Zr-Sn alloy was soaked in concentrated sulphuric acid, and pores in micro-level were formed on the surface of Zr-Sn alloy. To attain apatite forming ability in Zr-Sn alloy, second, apatite nuclei were formed in the micropores. To evaluate apatite-forming ability, thus-obtained Zr-Sn alloy with apatite nuclei was soaked in SBF; hydroxyapatite formation was observed on the whole surface of the Zr-Sn alloy plates. From this result, it was clarified that higher apatite-forming ability was attained on the apatite nuclei-treated Zr-Sn alloy with micropores in comparison with that without micropores. When adhesive strength of formed hydroxyapatite film with respect to Zr-Sn alloy plates was measured, high-adhesive strength of the formed apatite film was attained by forming micropores and subsequently precipitating apatite nuclei in the fabrication process because of an interlocking effect caused by hydroxyapatite formed in the micropores.