Abstract: An electric screwdriver includes a housing, a power output end, and a control cylinder mounting therein an active shaft connecting thereto a following shaft connecting thereto a driver mounting piece axially slidably mounted in a cap cylinder and a torsion-adjusting cylinder wherein the mounting piece has an engaging end attaching thereto a flange attaching thereon a light-shielding piece capable of shielding the light emitted by a photic control switch mounted on the control cylinder to allow the motor in the housing to be energized when the mounting piece mounts thereon a driver urging against a screw.