Because water content can be used identify a starch of unknown type, determining the water content of starch is very important in the quality control of processed food. Therefore, the following method was used in an attempt to determine the water content of several starches. First, NIR spectra were measured using a diffuse reflectance attachment equipped with optional fiber. The optional fiber simplified sample measurement. Next, the water content of each starch was approximated using the partial Least squares method(PLS), a multivariate analysis method.