A drill includes a pair of main cutting edges (A) extending from a distal portion of the drill to a position (G) close to a proximal end of the drill to entirely define a two-edge configuration, and a pair of auxiliary cutting edges (B) extending between positions at the distal and proximal sides (F and G) of a maximum diameter position (E) to partly define a four-edge configuration. A ridgeline (B1) of each auxiliary cutting edge (B) is located within an angle smaller than 90° from a ridgeline (A1) of the corresponding main cutting edge (A) toward the rear in a rotation direction of the drill. The point angle of the auxiliary cutting edges (B) increases at a higher rate than the point angle of the main cutting edges (A) in a predetermined range from the maximum diameter position (E) toward a distal end of the drill.