This invention realizes reduction in consumption of DC current in a level converter circuit by setting level shifters in an operating state only when necessary in accordance with hierarchical control, in which an output pulse of a level shifter (311) that is constantly in a power-ON state is used to set a level shifter (321) of the next hierarchical level in the operating state, then output pulses of the level shifter (311) and the level shifter (321) are used to generate control pulses LT1 and LT2, which are used to set level shifters (341 to 346) of the next hierarchical level in the operating state, and an output pulse of one of the level shifters is used to set level shifters (351), (352) and (353) of the next hierarchical level in the operating state. Thus, a level converter circuit in which the consumption of DC current is reduced and which enables reduction in power consumption of the whole device, a display device equipped with this level converter circuit, and a portable telephone device using the display device as an output display unit can be constructed.