To provide a power-on-reset device having a semiconductor circuit, in which the number of constitution elements is small and the area for layout is reduced, without having to use capacitors and resistors.

In a power-on-reset device generating a signal at turning on of the power supply of a power source unit, an output means 1 for notifying that the value of a supply voltage VDD has reached a value for operating a P-channel MOS transistor Mp, and an N-channel MOS transistor Mn is provided. Moreover, a means fo notifying that the supply voltage VDD has reached a sufficient value for operating the P-channel MOS transistor Mp and the N-channel MOS transistor Mn by other elements such as transistor elements M1, M3, M2, without resistive elements and capacitive elements.