Mapping system, mapping device and computer program

Provided is a mapping system characterized by comprising: a combine harvester that is provided with a reaping part (3) which is attached to a travelling part (1) that travels a field and which reaps grain culms of the field, a threshing device (2) which threshes the grain culms reaped by the reaping part, a discharge amount detection unit (4c) which detects, by means of grain collision, the discharge amount of grain discharged externally from the threshing device, positioning units (90, 98) which measure the position of the travelling part, and a transmission unit (95) which transmits the measurement results from the positioning units and the detection results from the discharge amount detection unit; a receiving unit (99e) which receives the measurement results and detection results transmitted by the transmission unit; and a discharge amount mapping unit (99) which, on the basis of the measurement results and detection results received by the receiving unit, associates the dischargeamount and a grain reapin