Near-infrared spectroscopy (NIRS) in the range 900–1700 nm was performed to develop a classifying model for dead seeds of mung bean using single kernel measurements. The use of the combination of transmission-absorption spectra and reflection-absorption spectra was determined to yield a better classification performance (87.88%) than the use of only transmissionabsorption spectra (81.31%). The effect of the orientation of the mung bean with respect to the light source on its absorbance was investigated. The results showed that hilum-down orientation exhibited the highest absorbance compared to the hilum-up and hilum-parallel-to-ground orientations. We subsequently examined the spectral information related to the seed orientation by developing a classifying model for seed orientation. The wavelengths associated with classification based on seed orientation were obtained. Finally, we determined that the re-developed classifying model excluding the wavelengths related to the seed orientation afforded better accuracy (89.39%) than that using the entire wavelength range (87.88%).