To improve the positional accuracy of a knife edge by reducing a fitting error of the knife edge position of a throwaway tip in a throwaway type cutting tool.

In this cutting tool 9 constructed by mounting the throwaway tip 10 on a holder 30, tapered constraint surfaces 16, 17 abutting on two tapered bearing surfaces 35, 36 formed on the holder 30, respectively, and similarly at least two constraint surfaces 14, 15 abutting on bearing surfaces 33, 34 substantially orthogonal to the substantially center line C between two tapered bearing surfaces 35, 36 formed on the holder 30 are formed on a tip 10. In locating and fixing the tip 10 on the holder 30, the positions in two directions substantially orthogonal to each other in the in-plane direction of the tip 10 are determined to fix the relative position of the tip 10 to the holder 30 substantially constant.