Reset device, circuit device, and resetting method

A reset device includes a power-on reset (POR) circuit configured to output a reset signal to reset a circuit part to an initial state when supply voltage is lower than a threshold level, a first switch provided in a path connecting a first line to supply the supply voltage to the circuit part and a second line to supply the supply voltage to the POR circuit, a second switch provided in a path connecting a signal line of the circuit part and the second line, and a control circuit configured to turn on the first switch and turn off the second switch in a normal mode, and to turn off the first switch and turn on the second switch in a test mode. The control circuit turns on the first switch and turns off the second switch in response to the reset signal being output from the POR circuit.