Abstract: A drill bit includes a cutting head and a bit body. The cutting head has a tip and cutting parts. The bit body is connected to the cutting head and has a longitudinal axis extending through the tip. The bit body has chip discharge flutes. The cutting parts are disposed at different angular positions around the longitudinal axis. Each cutting part is concaved inwardly and bounds one of the chip discharge flutes. Each of the cutting parts includes a rake face that has a corner edge adjacent to a respective one of the chip discharge flutes. When a bottom of the cutting head is viewed in a direction parallel to the longitudinal axis of the bit body, the corner edge has an obtuse included angle.