A Bessel beam is suitable for laser micro fabrication because it possesses both a small focal spot on the order of microns and a deep focal depth on the order of centimeters. In the case of laser micro grooving in stainless steel using a Bessel beam, suitable processing conditions were investigated. The results were compared with the results of micro grooving using a focused beam with a convex lens. In the grooving with the Bessel beam, it was possible to increase the groove depth while the groove width was kept almost constant. On the other hand, in the grooving with the focused beam, both the groove depth and the groove width increased when the irradiation energy was increased. A micro groove with an aspect ratio of about 5 and a width of about 2 μm was produced in a 10 μm thick stainless steel foil using a Bessel beam.