PROBLEM TO BE SOLVED: To provide a sheet that can prevent disconnection of a conductor contained in an electrode part which constitutes a heartbeat sensor.SOLUTION: The sheet includes: a heartbeat sensor having an electrode part 11 that detects a potential signal corresponding to the cardiac potential of a seated person； and an arithmetic processing unit that performs arithmetic calculation for specifying consciousness level of the seated person by means of the potential signal obtained from the heartbeat sensor. The electrode part 11 is composed of a conductive sheet 11a and a plurality of conductors 11d. The plurality of conductors 11d include: a basic conductor 11da that is arranged along the periphery of the conductive sheet 11a； and a plurality of cross conductors 11db that intersect the basic conductor 11da. The plurality of cross conductors 11db are not intersected partially at one place but intersected at a distance.SELECTED DRAWING: Figure 3
