Our challenge is to fabricate practical all-inorganic electroluminescent devices using colloidal quantum dots with presenting new aspects of electroluminescence mechanisms. The electric field effect on the excitation of a quantum dot with a hot electron that results in saturated chromatic electroluminescence was studied by time-resolved spectral transient properties at room temperature. Fast and very slow radiative recombination transition pathways are newly distinguished in the electroluminescence related to carrier confinement in the quantum dot under an electric field.