Cell nuclei is one of the most critical organelles in cells. Most information needed for life activities in cells, including DNA is stored in cell nuclei. With its position typically at the center of the cell, its universally believed that cell nucleus is the center for cell information storage and exchange. Terahertz electromagnetic waves have been found to be related to numerous neural activities, by means of information transmission. Therefore, the potential role of cell nucleus in intramolecular terahertz information transmission is up for discussion. By electromagnetic simulation of typical neuron nucleus, we discovered that the lipid bilayer of nuclei potentially confines terahertz waves in cells, similar to biological microcavities. Moreover, the structure of cell nucleus significantly responds to external terahertz fields. The intriguing character of nucleus’ responsiveness to terahertz fields exhibits the possibility of cell nuclei as terahertz microcavities in neurons. This study reveals a possible novel function of cell nucleus, and exhibits the possible role of terahertz waves in cell information storage and processing.