Integrated circuit device and fluorescent display tube

An objective of the present invention is to maintain the temperature of a filament constant. An integrated circuit device related to the present invention drives a filament in a fluorescent display tube with the filament emitting electrons. The integrated circuit device comprises: an output switch controlling output of a driving voltage for the filament; a detection unit detecting a current value of a driving current flowing through the filament or a voltage value of a driving voltage applied to the filament; and a control unit performing feedback control for controlling a switching operation of the output switch so that time product of two multiplication of either the current value the voltage value is constant based on the current value or the voltage value detected by the detection unit.