Abstract: A drill includes a substantially cylindrical bit body 10 having an axis O. The bit body 10 has a flange portion 13 which includes a converging portion 13a which reduces its diameter progressively towards the front end of the bit body and a flange 13b which is provided with a rearwardly facing annular surface 13c. The annular end surface is contactable with the front end surface of a drill holding portion of a machine too. Chip discharging flutes 14A,14B, each having an inner surface constituted by first and second inner surface portions 14a,14b and a third inner surface portion 14c arcuately recessed therefrom, are formed in the front end portion of the tip body 10. An inner peripheral cutting insert 16A and an outer peripheral cutting insert 16B are mounted on the ends of the chip-discharging flutes 14A,14B. The cross-sectional area S.sub.A of the first-mentioned chip-discharging flute 14A is determined to be greater than that S.sub.B of the second-mentioned chip-discharging flute 14B.