A power on reset circuit, comprising: a threshold level control circuit (120) configured to set threshold level values of power on reset and power off reset; a capacitor charge and discharge circuit (130) configured to output a power on reset signal according to the threshold level values set by the threshold level control circuit; and a current bias circuit (110) configured to provide a reference current not varying with a power supply to the threshold level control circuit (120) and the capacitor charge and discharge circuit (130), comprising: a first reference current output terminal connected to the threshold level control circuit (120); a second reference current output terminal connected to the capacitor charge and discharge circuit (130); and a third reference current output terminal connected to the capacitor charge and discharge circuit (130).