A positioning system includes a vehicular exterior communication device and a positioning device. The vehicular exterior communication device has an antenna and a strength detector. The antenna is disposed at a side surface portion of the vehicle that receives a wireless signal transmitted from the portable terminal. The strength detector detects reception strength of the wireless signal received by the antenna. The positioning device determines whether the portable terminal is present at an operating area based on vehicular exterior device strength as the reception strength of the wireless signal from the portable terminal detected by the vehicular exterior communication device. The vehicular exterior communication device is disposed under a door of the vehicle in a posture in which a center of directivity of the antenna faces upward or downward.