A wearable camera captures an image of a capturing area, and a vehicle-mounted camera captures an image of the capturing area. The wearable camera records first image data of the capturing area in the wearable camera. The wearable camera repeatedly transmits information related to a recording amount of the first image data to the vehicle-mounted recorder. The vehicle-mounted recorder receives the information related to the recording amount of the first image data transmitted from the wearable camera. The vehicle-mounted recorder records second image data of the capturing area captured by the vehicle-mounted camera in the vehicle-mounted recorder when the recording amount of the first image data exceeds a set value.