An electron emission device includes a first substrate; a second substrate facing the first substrate and spaced apart from the first substrate; an electron emission unit on the first substrate, the electron emission unit having at least two electrodes and an emission region for emitting electrons; and a light emission unit on the second substrate to be excited by a beam formed with the electrons. The electron emission unit includes a focusing electrode for focusing the beam. The light emission unit includes a screen on which pixels are arranged in a pattern. Each of the pixels has a phosphor layer. The phosphor layer of one of the pixels is excited by the beam. The focusing electrode includes an opening, through which the beam passes. A length of the opening is LV, a pitch of a pixel is PV, and LV and PV satisfy: 0.25 ≦LV/PV≦0.60.