The photocarrier generation mechanism has been studied in a highly sensitive layered organic photoreceptor for laser beam printers. A series of experiments has been carried out on a layered photoreceptor which has a carrier generation layer (CGL) containing a triphenylamine trisazo pigment as the main component. As a result, we have found that (1) excitons are produced in the bulk of the CGL by photon absorption, (2) the excitons dissociate into free carriers (negative electrons and positive holes) at the interface between the CGL and a carrier transport layer (CTL), and (3) all positive holes are immediately injected into the CTL. The mechanism of photocarrier generation is considered to be based on a photoinduced electron transfer reaction from the ionization potential level of the carrier transport material in the ground state to the ionization potential level of the photoexcited carrier generation material.