A bed occupancy state detection method includes detecting loads applied to a head side right portion, a head side left portion, a foot side right portion, and a foot side left portion of a bed platform by first to fourth load detecters, respectively, judging whether or not a prescribed judgment formula is satisfied based on load values outputted from the first to fourth load detecters, and notifying information on a bed occupancy state of an object in cases where it is judged that a judgment formula is satisfied from a judgment result at the judgment.