Disclosed is a diamond tool having a metal plate inserted therein. Between abrasive layers containing diamond particles is inserted a ferrous or non-ferrous metal plate having a wear resistance lower than that of the abrasive layers such that a concave groove is spontaneously formed during a cutting process, thereby reducing the contact load with a workpiece to thereby avoid vibration (wobbling) of a shank, and providing a discharge path for smoothly removing cutting chips and the cooling water. In addition, the content of abrasives and the wear resistance of bonding material are uniformly constituted so that the shrinkage rate does not need to be considered during sintering and the manufacturing process can be simplified, thereby reducing the manufacturing cost and improving the productivity therefor. Furthermore, the area of the metal plate can be controlled, thereby enabling an easy design conforming to the working conditions with a workpiece.