To provide a small diametrical drill for deep hole drilling excellent in cutting fluid supplying capacity to a drill knife edge even though it is structured simple without an oil hole, capable of improving a cutting chip discharging property and capable of carrying out small diametrical deep hole drilling of a diameter of less than about 3 mm and more than 5D efficiently and at low cost.

This drill forming a cutting chip discharging groove 4 along the longitudinal direction on an outer periphery is provided with a plurality of cutting fluid introduction grooves 5 having a left inclination to take up cutting fluid by centrifugal force by rotation of the drill and to forcibly deliver it in the direction of the drill knife edge on an upper margin part except for a position of 3D from a tip and a cutting fluid supplying groove 6 to make the cutting fluid taken up in the cutting fluid introduction grooves 5 reach the knife edge by vertically connecting the cutting fluid introduction grooves 5.