Titanium (Ti) metal substrates were etched in sulfuric acid (H₂SO₄) with concentrations of 25, 50, 75 and 97% at 60°C for 30 min. Hydroxyapatite (HA) films were deposited onto unetched and etched substrates by an electrodeposition method under a pulse current. The electrolyte was metastable calcium phosphate solution that had 1.5 times the ion concentrations of human body fluid, but did not contain magnesium ion at 36.5°C. Deposition times were 90 min. We used the average current density of 0.01 A/cm² and ON time equal to OFF time of 15 s. In the electrodeposition, hydrogen was incorporated into the surface of the Ti substrates to form titanium hydride (TiH₂) on the substrate surfaces. After the electrodeposition, all specimens were heated at 600°C for 60 min. The adhesion between apatite and substrates were greatly improved by the heat treatment for the substrates etched in 50 and 75% H₂SO₄. It is considered that in these specimens the anchoring effect due to the microstructural roughness formed by etching was enhanced by the shrinking of HA crystals during the heat treatment.