A detection area adjustment apparatus automatically detects the entire target detection area without producing any dead areas and without requiring cameras to be previously fixed at regular intervals, even in the case where a camera is broken. The detection area adjustment apparatus includes plural camera terminals. Each of the plural camera terminals includes a camera whose detection area is adjustable, an adjustment unit that adjusts the position of the detection area by controlling the camera, and a communication unit that communicates the detection area information indicating the detection area of the camera. The adjustment unit adjusts the position of the detection area of the camera in the current camera terminal so that the total area of the detection areas of the plural camera terminals covers the entire target detection area based on the detection area of the camera in the current camera terminal and the detection areas of the cameras in the other camera terminals.