We have applied time-resolved absorption spectroscopy to the study on the photocarrier generation process in layered organic photoreceptors. The photoreceptors are comprised of azo-pigments as charge generation materials (CGMs) and charge transport materials (CTMs). Two or three distinct transient absorptions ranging from visible to mid-infrared wavelength region (600 – 2500 nm) were observed after photoexcitation in these photoreceptors. We ascribed all these transients to the cationic species of CTMs from the results of the measurements in various conditions. The transient absorption spectrum showed remarkable dependence on the CTM concentration. From this observation, we concluded that the cationic species of CTMs were monomer, dimer and larger aggregate cations. The latter two cationic species are regarded as the holes delocalized within some CTM molecules. The role of delocalized holes in photocarrier generation is discussed from the decay dynamics.