Near-infrared spectroscopy (NIRS) calibration models for determining grain constituent contents at grain elevators were developed using rice and wheat grown in Hokkaido. The coefficient of determination (r²), standard error of prediction (SEP) and ratio of standard error of prediction to standard deviation (RPD) of the validation statistics were r² > 0.99, SEP = 0.19 % and RPD = 25.2 for brown rice moisture content, r² = 0.99, SEP = 0.09 % and RPD = 9.8 for milled rice protein content, r² > 0.99, SEP = 0.34 % and RPD = 23.1 for wheat moisture content and r² = 0.97, SEP = 0.31 % and RPD = 5.4 for wheat protein content. These results indicated that the accuracy of NIRS was sufficiently high for practical use at grain elevators.