A dust-proof circular saw includes a base placed on a workpiece, a circular saw main body supported on an upper surface side of the base and equipped with an electric motor, and a saw blade driven by the electric motor extending downwardly from the base. The dust-proof circular saw further includes a cooling fan driven by the electric motor to guide air to the electric motor for cooling the electric motor, as well as to a blower mechanism. The blower mechanism blows the cutting chips away by blowing the air generated by the fan out of the circular saw main body in a user-adjustable direction. The blower mechanism has an air outlet configured to blow out the air, and an orientation change mechanism capable of changing the orientation of the air outlet.