A parking management system includes a reading device, a vehicle detection device, and a parking management device. The reading device reads identification information for identifying a vehicle from an identifying body mounted on the vehicle that enters a boundary of a management area including parking spaces in each of which one vehicle can be parked. The vehicle detection device detects the vehicle that exists in each of the parking spaces. When the identical identification information is not read again during a passing determination time from a time point at which the identification information is initially read by the reading device, and when a new vehicle is detected in the parking space by the vehicle detection device during the passing determination time, the parking management device determines that the vehicle indicated by the identification information is parked in the parking space.