1. A monitoring system comprising: a camera server that has a camera whose image pickup direction is controllable; and a setting client at which a tracking method of the camera server is set through a network, wherein the camera server includes: detection means for detecting a moving object in a picked-up image obtained from the camera, based on preset setting information of the tracking method; tracking control means for controlling the camera to perform tracking based on a result of the detection by the detection means; and transmission means for sending the result of the detection by the detection means and the picked-up image to the setting client, and the setting client includes: reception means for receiving the result of the detection by the detection means and the picked-up image from the camera server; window display means for displaying an image display window, in which the received picked-up image obtained from the camera and an indicator to indicate a change detection maximum area as the result of the detection by the detection means are superimposingly displayed, and a setting window to make a setting of a tracking method by referring to an image displayed in the image display window; and transmission means for, when detected that setting information concerning a setting of the tracking control means has been changed through the setting window, sending the changed setting information to the camera server.