Abstract: The present invention is a toilet stool seat disinfecting apparatus comprising a body mounted in the rear portion of a toilet stool, a ray sensor unit installed in the body to detect the opening of the stool cover, a pair of nozzles installed at both sides of the body, the nozzles being connected to a disinfectant source through a flow way, and a controller circuit which controls opening of a flow way when the ray sensor detects the opening of the stool cover. The apparatus automatically sprays disinfectant to the stool seat when the stool cover is opened by a user of the toilet stool.