A system for detecting a target object includes a first detector that detects an object by emitting radio waves and receiving reflected waves that are the emitted radio waves reflected by a target object, a second detector that detects heat generated by the target object, and an information collection apparatus that determines the presence or absence of the target object on the basis of the detected reflected waves and the detected heat, and the information collection apparatus determines the presence of the target object in a case where the first detector has detected a movement of the target object and the second detector has detected the heat.