A log generator generates log data including a processing time and processing contents, as data indicating a history of each of processes including input of video data recorded in a storage of a case video management system by a video input unit, image processing including a masking process to be performed on the video data by an image processor, and output of the video data by an encoder and a video output unit, at the time of performing processing for the video data, and records the log data in the case video management system in association with the processed video data.