To provide a cutter with an air exhaust mechanism provided with a hard layer on the surface of a chip guide member.

A chip discharge groove 6 is formed at the outer peripheral part of a cutter body 1. A chip guide member 7 is disposed at the end face side opening of the chip discharge groove 6, and a clearance t is formed between the chip guide member 7 and a rake face of a cutting edge tip 2. In order to improve wear resistance, the surface of the chip guide member 7 is formed with a hard layer of TiC, TiN, TiCN, TiAlN, or the like by a physical vapor deposition method, or a hard layer by nitriding, carburization or boronizing treatment.