A test circuit first detects whether or not a relay unit is normal, and then examines an operation of leakage detecting circuit. This allows relay unit to interrupt an electric power supply path including power lines more securely if electrical leakage occurs in the electric power supply path. If welding in the contact of the relay unit is detected before starting charging of a power storage device included in an electrical device, a control device does not allow the charging of the power storage device, which can prevent a problem from occurring in the electrical device.