A rush current limiting device capable of restraining increased power consumption and heat generation caused by resistance for limiting rush current, and effectively limiting rush current caused on any conditions has. A resistance for limiting rush current caused by switching of a power switch between a rectifier diode bridge and a smoothing condenser. A triode AC switch and the relay are provided in parallel with the resistance. The on-operation of a power switch is monitored by the input monitoring circuit, and an triode AC switch is turned on at the zero crossing point of input signals after the on-operation by the zero crossing circuit to short-circuit the resistance. After a delay of the relay due to sensitive time, the relay is turned on by a relay driving circuit, and the triode AC switch is turned on.