It is an object of the present invention to provide a cutting tool in which excellent electrical conductivity between a tool substrate and a workpiece can be realized even when the tool substrate is clad with a diamond film, and with which it is possible to precisely control the hole boring depth or precisely sense breakage by using the electrical conductivity. An electroconductive film (3) is provided to a diamond film (2) at a site that will make contact with a workpiece or around the site so as to conduct electricity with a tool substrate (1).