To heighten the tolerance to defects during producing process by forming a plurality of emitter regions provided with a plurality of emitters and forming cathode lines for respective regions in a manner that respective regions can be driven independently.

A cathode line A20 and a cathode line B21 are formed like stripes in approximately the center of anode 1 dots 70. That is, two cathode lines are formed for each dot 70 and a plurality of linearly arranged emitters 40 are formed respectively in the line A20 and the line B21. Moreover, since two cathode lines are formed for each dot 70, in the case defect is found in a part of the emitter 40 formed, for example, in the line B21, the line B21 is not used and the other line is used instead. Consequently, since an emitter region in which a defect emitter shot circuited from the gate electrode can be made no need of using, the tolerance for defects during the producing process can be heightened.