Since many intra/intermolecular vibration modes of biomaterials such as protein1, 2 and DNA3–6 are located within THz spectral range, there has been great interest in research with THz spectroscopic system for biomaterials. Specifically, in contrast to other optical techniques including ultraviolet or X-rays, its non-invasive and non-ionizing properties allow THz technique to be utilized as spectroscopy for even more complex structural biomaterials comprising cells7 and tissues8 without worrying about thermal fluctuations or other nonlinear side effects. In protein, especially, the conformational information plays a major role in molecular interactions and binding with ligands, which can be analyzed by the THz spectroscopy9, since the protein-ligand binding energy is in the THz range as well. However, the detection of such small change of optical property could be limited using THz spectroscopic system as it is, due to its too small absorption cross-section. Recently, metamaterial sensing chip based THz detection techniques have been developed for highly sensitive and selective detections of carbohydrates10, chemical compounds11, 12, thin sample layer13, 14 and microorganisms15 and overcoming the limit of sensitivity with typical THz spectroscopic systems. Here, we report THz optical characteristics of three different AI viruses investigated using a highly sensitive THz spectroscopy system assisted by nanoscale metamaterial sensing chips. The sensing chip induces huge THz field enhancement16 as much as 50 times, leading to increase the detection sensitivity and selectivity at the same time. Therefore, the three different AI virus samples could be clearly discriminated with respect to their optical parameters. The quantification for one of the virus subtypes was also performed verifying the excellence of the THz nano-metamaterial sensing chip, finally.