Parking detection sensor (100) has a Doppler sensor (110), a magnetic sensor (120) that detects magnetism on XYZ axes, a change point detection unit (130) that detects a change point in the output of the Doppler sensor (110) and the magnetic sensor (120), a level difference detection unit (140) that detects the magnetic level difference over time in the output of the Doppler sensor (110) and the magnetic sensor (120), and a state assessment unit (150) that assesses the parking state of a vehicle on the basis of the detection results of the change point detection unit (130) and the detection results of the level difference detection unit (140).