Hydroxyapatite (HAp) has unique properties for biomaterials such as hard-tissue-compatible material for bone and tooth and also soft-tissue-compatible materials for skin tissue. However, the hard and brittle nature of HAp limits spreading many medical devices. Recently, a unique composite of sintered HAp nano-crystals -- ceramics -- covalently coupled to polymer substrates was developed -- Nano-Ceramic Coating --. The development was depended on the two original technologies: (1) control of size/morphology of high-dispersed sintered nano-HAp, (2) donation of covalent bonding between nano-HAp and substrates to coat strongly on the surface. The nano-composite material holds not only the mechanical properties of the substrate but also biological properties of the ceramics coated on the surface. In this report, the method of synthesis of high-dispersed nano-HAp, the preparation of the nano-composite, the biological properties with cells or animal tissue, and especially, the development of medical devices, such as percutaneous device or blood vessel and so on, made of the composite will be presented.