Electronic states and direct interband light absorption in the ensemble of prolate spheroidal quantum layers are considered. The problem of finding the one-electron wave function and energy spectrum have been solved exactly. Absorption edge dependence on the thickness of the layer in the strong size quantization regime has been obtained. The effect of nonparabolicity of the dispersion law of energy levels and optical absorption have been taken into account and calculations are carried out for the cases of both parabolic and Kane’s dispersion laws. Selection rules have been revealed. Absorption coefficient dependence on the frequency of incident light has been obtained, taking into account dispersion of nanolayer thicknesses for the cases of both symmetric and asymmetric distribution functions.