Provided is an electron emitting device which can achieve high electron emission efficiency even in the case where excitation energy is low. The device includes a carbon nanotube layer which is formed on an SiC substrate and is made up of plural carbon nanotubes vertically oriented with respect to a surface of the SiC substrate; an MgO layer which is formed on and touches the carbon nanotube layer; an ohmic electrode which is connected to the carbon nanotube layer; an electrode which is facing the MgO layer with an air-gap between the MgO layer and the electrode; and a voltage source which applies a voltage between the electrode and the ohmic electrode.