In this study, we demonstrated the improvement in the biocompatibility of titanium alloy by atmosphericpressure-plasma nitriding, in which the pulsed-arc plasma jet is sprayed onto a titanium alloy to form TiN surface. The deposition properties of calcium phosphate on different samples were compared after immersion in simulated body fluid to investigate hard-tissue compatibility. It was determined that the growth of the calcium phosphate layer on the nitrided sample was the most rapid. This result suggests that atmospheric-pressure-plasma nitriding has the potential to easily improve the hard-tissue compatibility of titanium alloy.