To provide a drill bit having constitution where the body is made of a solid rod and whose tip has a hard cutting edge since its diameter is small, in which a medium for cooling fed from the outside for cooling the tip cutting edge side generating heat upon drilling is received at the root side and can be securely passed to the tip part.

In the drill bit having the constitution where the body is made of the solid rod and whose tip has the hard cutting edge, the part from the root side to the tip cutting edge side of the solid rod-shaped body is covered with an outer cylinder which does not rotate, the medium for cooling fed from the outside with a hose or the like is connected to the root side receiving port of the outer cylinder to be received, is taken into a space between the inner circumferential face of the outer cylinder and the outer circumferential surface of the body, and is securely passed to the tip cutting edge side.