1. A method of optimizing an NMR measurement condition, comprising the steps of: gaining NMR measurement data while varying the value of the NMR measurement condition to be optimized; extracting a certain property as a numerical value from the measurement data; plotting the numerical value of the measurement data versus the varied value of the measurement condition to create a curve; setting a model equation coincident with the measurement condition, its range, and the certain property extracted as a numerical value; performing curve fitting in which constants of the model equation are varied such that the model equation agrees with the created curve; and gaining constant values of the model equation and their standard deviation by curve fitting and obtaining an optimum value of the measurement condition from the gained constant values and standard deviation.