There is provided a body state detecting apparatus for detecting a body state of a subject on a bed, the apparatus including: a plurality of load detectors which are placed in the bed or under feet of the bed and which detect a load variation depending on a respiration of the subject； and a body state detecting unit which determines an extending direction of a body axis of the subject and a head placement of the subject based on the detected load variation. The body state detecting unit includes a body axis direction determining unit which determines the extending direction of the body axis of the subject based on the detected load variation, and a head placement determining unit which determines the head placement of the subject, in the determined extending direction of the body axis of the subject, based on the detected load variation.
