A grain management system includes a combine and a management server 8. The combine includes a grain measurer 30 for outputting a measured value related to a component of harvested grains supplied to a grain tank 16, and a data transmitter 51a for transmitting the measured value and field identification information for specifying the field to the management server 8 via a communication line. The management server 8 includes a receiver 81b for receiving the field identification information and the measured value from the combine, a table manager 83 for determining a measured value-grain component value table for deriving a grain component value using the measured value based on the field identification information, and a grain component value computer 82 for obtaining the grain component value based on the measured value, using the measured value-grain component value table that is determined by the table manager 83.
