ELID grinding is a method that realizes high quality mirror surface grinding in the nanometer order by use of electrolytically dressing metal-bonded wheels consisting of fine abrasives. Currently, ELID grinding is increasingly being applied as an ultra-precision grinding method to achieve desired surface roughness, high surface accuracy, high surface quality, and high grinding performance. This paper introduces the principle of ELID grinding and discusses some applications of ELID grinding to mirror surface grinding.