An accident judgment device (105) judges whether or not an accident has occurred based on a detection signal of an impact sensor (104). Upon judging that an accident has occurred, an image saving device (106) extracts an image within several seconds before and after occurrence of the accident from a ring buffer (103) to save the same in a save memory (107). Upon judging that the accident has occurred, an image-record requesting device (108) transmits an image-recording request to a drive recorder (10) of target vehicles existing in the vicinity of the accident spot. Upon receiving the image-recording request, an image saving device (106) of the drive recorder (10) on the target vehicle extracts the image within several seconds before and after occurrence of the accident from the ring buffer (103) to save the same into the save memory (107).