In this study, bone-like apatite formation on manganese-hydroxyapatite (Mn-HA) coatings formed on Ti-6Al-4V by plasma electrolytic oxidation (PEO) has been investigated by several techniques. Ti-6Al-4V ELI disks were used as substrates for PEO treatment. Test specimens were used as anodes, and a Pt rod was used as the cathode in an electrolytic solution containing Mn. The applied voltage was 280V, and the deposition time was 3min. To examine the bioactivity, the PEO films formed on Ti-6Al-4V were immersed in SBF for 12h. The PEO films and the Ti-6Al-4V surface after immersion in SBF were characterized by a thin-film X-ray diffractometer, field-emission scanning electron microscopy, and energy dispersive X-ray spectroscopy.The PEO surface presented large and irregular pores, and the number of pores increased as the Mn content increased. For the PEO-treated samples, anatase peaks were detected by X-ray diffraction, and the HA peak intensity increased as the Mn content increased. The Ca/P ratio decreased, whereas the (Ca+Mn)/P ratio increased, as the Mn content increased. The coatings without Mn on the micropores had a small granular shape, and the pores were covered with HA after the immersion in SBF. As the Mn concentration increased, all Mn-HA coating surfaces became more dense, and microcracks appeared on the coating surface.