Diamond is nominated as a material candidate for future high power device due to its superior material properties and resulting very high FOM. In this paper, our recent progresses and the expected possibilities of diamond for power electronics applications are introduced as short review. Firstly for the epitaxial growth, by adopting step-flow epitaxial growth by off- angle substrate with optimized growth conditions, we have succeeded in reducing these killer defects almost six orders from 106cm-2 to almost 100cm-2 levels. For the substrate, our recently developed technology to fabricate diamond plates from bulk, 12x13mm2 size are available to use, that can avoid fabrication difficulties with small size substrate. Secondly for the device, primitive studies showed possibly for the advantage of diamond such as low reverse leakage current, high temperature and high current density operation.