A metal working oil composition which is used for a very small amount of oil-feeding type metal working methods comprising a base oil selected from the group consisting of natural fats, derivatives thereof and synthetic ester oils, and a phospholipid is disclosed. The metal working oil composition of the present invention has good lubricating properties and is suitable for processing metallic materials such as cast irons steel, stainless steel and the like by the very small amount of oil-feeding type metal working method.