To prevent a screw from deflecting with respect to a soft member and lessen the shock generated at the time of biting into a metal member.

This drill screw is composed of a head 2 and a leg part 3 continued from it and having a threaded portion 10, and the leg part 3 is furnished with a drill part 12 approximately in a conical shape and two exhaust grooves 13 extending at diagonal positions pinching the axis, and blades 20 furnished with machining edges 21 are provided along the exhaust groove 13. Because each machining edge 21 is formed in a circular arc from the forefront to the side edge, the thickness of a metal member as the mating member becomes relatively large, and it is possible to drive in stably even if the arrangement requires a large thrust force. Because the forefront of each blade of this drill screw is shaped in a circular arc, no large reaction force acts steeply when the blade bites into the metal member to allow the operator to have a reduced fatigue, and the deflection of the screw to a soft member such as wood or plywood can be eliminated.