Position-detecting device, respiration measurement device and heart rate measurement device

To provide a position-detecting device capable of efficiently detecting the position of various sections of a recumbent person's body as well as providing a respiration-detecting device and a heart rate measurement device using said position-detecting device. [Solution] The position-detecting device (1) is provided with: a body pressure distribution sensor (4) in which multiple pressure sensors (41) that are each capable of outputting a pressure signal corresponding to a pressure value (42) are disposed in a matrix form; a specifying pattern-storing means for storing, as a specifying pattern, the area of pressure sensors (41, 41 ...) occupied and the conditions of the pressure values (42, 42 ...) associated with the pressure sensors (41, 41 ...) in said area for each recumbent posture and body region of a recumbent person (A); a scanning means for applying a specifying pattern sequentially to body pressure distribution information (44), which is a set of pressure values (42, 42 ...), from a scan starting position to an adjacent position and assessing the conditions; and a body region position-determining means for determining, when conditions are satisfied, the position of the corresponding body region in the recumbent position on the basis of the position that the specifying pattern occupies in the body pressure distribution information (44).