To provide a cutting tool having cutting performance not less than a conical bit, manufacturable at a low cost and usable for a header or an undercutting header equipped with the conical bit.

The disk bit is composed of a cutter formed by providing a support shaft protrusively on one side of a disk made of steel or a disk comprising a cemented carbide tip and wear-resistant padding, and a holding base for supporting the support shaft rotatably. Two kinds of disk bits are arranged at the cutter head drum so as to have different cutting lines with the different directions of the support shafts and the different positions of disk blade edges to constitute the cutter head with one disk bit formed as an undercutting disk bit for separating and cutting a rock bed and with the other disk bit formed as a scraper disk bit for compression-crushing the rock bed.