A surveillance system having a multi-area motion-detection function is described. The surveillance system includes a display, an area selection device, and a threshold input device. The display shows a surveillance video. The area selection device selects a first area and a second area on the display screen. The threshold input device sets a motion-detection threshold of the first area and a motion-detection threshold of the second area. When the result of the motion-detection exceeds the motion-detection threshold of the first area, the surveillance video is stored in a storage medium. When the result of the motion-detection exceeds the motion-detection threshold of the second area, the surveillance video is stored in the storage medium.