various studies on groove machining of single-crystal silicon have been done because it is used extensively as semiconductor devices. Micro groove machining is expected as the application for reaction promotion of chemical catalyst to increase material surface area to form micro grooves in material surface. Therefore, groove microfabrication technology of high hardness steel is strongly expected to establish. This machining method is also expected to apply as the new die machining. In this report, the micro groove machining of steel material using cBN blade is realized with accurate groove profile that depth is 100μm. The burr height, karf width and microasperity of groove bottom are evaluated under the various machining conditions.