PURPOSE: To improve the withstand voltage across stem pins by adjacently arranging a stem pin connected to an electrode applied with the highest voltage of an electron gun and a dummy pin applied with the intermediate voltage between the maximum voltage applied to the electron gun and the second highest voltage.

CONSTITUTION: An electron gun 19 is stored in the neck section 16 of a bulb 15, and the electron gun 19 is formed, for example, by coaxially arranging a directly heated cathode and electrodes G1WG5 of the first W fifth grids. Individual pins P1WP7 of a stem are arranged apart at an angle of 45° on a concentric circle of the stem 20; the pin P1 is connected to the electrode G1, P2 and P4 to the cathode heater, P3 to the electrode G2, P4 to the electrode G4, P7 to the electrodes G3, G5 respectively; and the dummy pin P6 is applied with the intermediate voltage between the highest voltage HV applied to P7 and the second highest voltage Vg3 applied to P5. Accordingly, the withstand voltage across the stem pins can be improved, thus allowing to use a button-less anode.