In a power-on detection circuit, a first connection node at which a first divided voltage is generated is connected to a second power supply line during activation of a power-down detection signal. Inactivation timing of the power-down detection signal is set earlier than an activation timing of a power-on detection signal. Therefore, the first transistor whose gate is connected to the first connection node is certainly turned off in the first half of a power-on period, which prevents the power-on detection signal from being activated during the power-on period. Further, a leak current flowing through the first transistor is reduced. In the second half of the power-on period, the power-on detection signal is certainly generated using the first divided voltage generated by the first dividing circuit. Thus, operating a reset circuit without malfunction and normally outputting a reset signal is possible disregarding behavior of a power supply voltage at power-on.