We measured the terahertz vibrational spectra of a solid solution Of L-asparagine and L-aspartic acid monohydrate at 0.5 to 6.0THz using a GaP Raman THz spectrometer. The absorption peaks at below 2.5 THz clearly showed intensity changes reflecting the change in hydrogen bonding between molecules. The peaks in the higher frequency region were indirectly affected by intermolecular bonding, which resulted in broadening.