To reduce the cost of replacing cutter bits and enhance the efficiency of a long-distance boring operation in a multi-geological layer by enabling drilling using tips matching different geological features in the ground of a multi-geological layer, extending the service life of the cutter bit, and reducing the number of times that the cutter bit is replaced.

The cutter bit 1 has a base metal 3 mounted at the end of a boring machine, and hard tips 2 driven into the end face 3a of the base metal 3 with the ends of the tips protruding. The tips 2 are driven in a plurality of steps from front to rear ends. At least some of the steps of tips 2 are made from a material different from the material from which the other steps of tips are made.