A window operator with means for electric operation of windows and comprising a magazine (8, 9) for an opening member (80), a drive member (10) for the opening member (80), an electric motor (5) and a worm gear (15, 40) coupled with the shaft (41) of the motor. A preferably static self-locking reduction gear is inserted between the worm gear (40, 15) and the drive member (10). The worm (40) and the worm wheel (15) of the worm gear are furthermore supported so that their respective axes of rotation (41, 63) are mutually movable.