To prevent an occurrence of a false report when a person passes by a bed while moving an object with wheels.

A mat sensor 1 for detecting an object that is present near a patient's bed and including a plurality of detecting sections 3 disposed across the entire area is installed. When a detecting section 3 adjacent to the detection section 3 detects a load during lapse of a prescribed time from when a detecting section 3 disposed at an edge of the mat sensor 1 has detected the load, the loads are linearly detected from the edge of the mat sensor 1, so that it is determined that an object with wheels passes on the mat sensor 1 and no notification is made. Alternatively, when a detecting section 3 that is not adjacent to the detection section 3 detects the load during lapse of the prescribed time or, when a detecting section 3 that is disposed at a part other than the edge of the mat sensor 1 detects a load, while no time measurement is performed, dot-like loads are detected at the central part of the mat sensor 1, so that it is determined that a person gets on the mat sensor 1 and a notification is made.