[Object][Solving Means] A discharge device includes a discharge unit and a cut-off detection unit. The discharge unit is configured to discharge a capacitor at a variable discharge current value on the basis of a voltage of a rectified signal obtained by full-wave rectifying an AC voltage input via an input filter including the capacitor. The cut-off detection unit is configured to monitor the voltage of the rectified signal and to detect whether or not a power supply is cut off on the basis of a change of the voltage when the capacitor is discharged by the discharge unit at a specific discharge current value.