A detection system includes a plurality of support posts, cables supported by the support posts, a winding device operable to wind the cable, a lifting and lowering device that is connected to the cable, and is movable in an air when the cable is wound by the winding device, and a detecting device hung by the lifting and lowering device. The detecting device is configured to be moved by the winding device in a region defined by the support posts, and lowered by the lifting and lowering device to detect information concerning an object.