A regulator circuit is offered to resolve a problem that an unnecessary operating current flows in a semiconductor integrated circuit in a low power consumption state. Channel width to channel length ratios of an output transistor in a first operational amplifier and a first control MOS transistor are designed large in order to obtain an operating current in a normal operation state, while channel width to channel length ratios of an output transistor in a second operational amplifier and a second control MOS transistor are designed small to obtain an operating current in the low power consumption state. There is provided a switching circuit that selectively put in operation one of the operational amplifiers according to the state of the integrated circuit. The first operational amplifier and the first control MOS transistor having higher current driving capabilities operate in the normal operation state. The second operational amplifier and the second control MOS transistor having lower current driving capabilities operate in the low power consumption state.