A screw driving machine includes a bit that is movable to strike a screw against a workpiece and rotatable to rotate the screw to the workpiece, a combustion-type power mechanism including a spark plug that ignites combustible gas filled in a combustion chamber to apply striking force to cause the bit to strike the screw, a motor that generates a rotative force when supplied with electric force, and a power transmission mechanism that transmits the rotative force generated at the motor to the bit to cause the bit to rotate.