A drill capable of drilling a deep hole while keeping high chip discharging ability and having a helical flute (6) whose width and helix angle ( alpha ) will not change even after the cutting edges have been regenerated by regrinding. The drill has a tip portion (1) formed with a helical flute having a constant width and helix angle ( alpha 1), a rear portion (3) formed with a helical flute which are greater in width and smaller in helix angle ( alpha 3) than the helical flute formed in the tip portion, and a middle portion (2) provided between the tip portion and rear portion and formed with a helical flute smoothly connecting with the helical flutes of the tip portion and rear portion and having a gradually increasing width and a gradually decreasing helix angle ( alpha 2) from the tip portion toward the rear portion. <IMAGE>
