Abstract: A control device is connected to a control-target machine and an imaging device (22). The control device includes a first receiver (41) to repetitively receive image data indicating an image captured by the imaging device (22) and containing a first timestamp indicating an elapsed time since a specific time in association with the image, a second receiver (42) to receive communication data related to a history of communication at the imaging device (22) and containing a second timestamp indicating an elapsed time since the specific time and transmission time data indicating a transmission time of transmitting the communication data, and a recorder (43) to cause storages (433, 44) to store association data on the basis of comparison between the first timestamp and the second timestamp that corresponds to the transmission time. The association data indicates a corresponding time corresponding to the first timestamp in association with the image.