In order to improve durability, machining stability, machining accuracy, etc. of a throwaway cutting tool in which a cutting head having a cutting edge is detachably mounted to the tip of a tool body using a clamping tool so that its function can be regenerated by replacing the cutting head, protrusions 8, 16 having their height gradually increasing and recesses 9, 15 having their depth gradually increasing from the center toward outer periphery of the tool are formed alternately with each other in a radial arrangement on the front surface of the tool body 2 and a support surface of the cutting head 3, which is formed by sintering, respectively. The protrusions and recesses, which are provided so that their positions correspond to each other, are conically engaged, thereby centering the cutting head and preventing its movement.