Abstract: A porous iron system metal bond diamond grinder using diamond as grinding particles and iron system metal powder as binder so as to have a large number of pores in the binder. The grinding particles are chemically and physically combined with the iron system metal to be held. The occupancy rate of pores in the whole grinder is 5 to 60%. The iron system metal is selected from a group composed of mixtures of iron powder, carbon-coated iron powder, iron nitride powder, carbon and iron. Carbon of diamond constituting the grinding particles is reacted to the iron system metal in the surface. In the manufacturing method, grinding particles and binder are mixed and molded into a predetermined shape and the molded product is then heated and sintered at 900.degree. to 1150.degree. C. The occupancy rate of pores and/or the concentration gradient of diamond are adjusted. The porous iron system metal bond diamond grinder capable of performing grinding continuously for a long time without loading can be provided.