To provide a back surface grid type fluorescent display tube prevented from leakage light emission caused by an electric potential impressed on dampers for preventing vibration of a filament.

A filament F and dampers D1 to D4 are arranged between the back surface grids G1 to G4 and anode electrodes A1 to A4. The anode electrode A1 is lighted because a (+) potential is impressed on it and a (+) potential is also impressed on the back surface grid G1. At that time, the electric potential of the damper D1 does not hinder the lighting of the anode electrode A1 because a (+) potential corresponding to the back surface grid G1 is impressed on the damper D1. On the other hand, the anode electrode A3 is not lighted because a (-) potential is impressed on the back surface grid G3 though a (+) potential is impressed on the anode electrode A3. At that time, the leakage light emission is not generated at the anode electrode 3 due to the electric potential of the damper D3 because a (-) potential corresponding to the back surface grid D3 is impressed on the damper D3.