<b>Highly Conserved Binding Region of ACE2 as Receptor for SARS CoV 2 between Human and Mammals</b> In Belgium, case of new coronavirus, severe acute respiratory syndrome coronavirus 2 SARS CoV 2 infection from owner to domestic cat was reported on March 27, 2020. So far, cases of SARS CoV 2 infection from owners to their dogs have been reported. For the first time in the world, the case of SARS CoV 2 transmission from the owner to a domestic cat has been confirmed. A tiger kept at a zoo in New York, USA, was reportedly infected with SRAS CoV 2. It is believed that SRAS CoV 2 has been transmitted to tiger from caretakers infected with SRAS CoV 2. Therefore, we examined the homology of whole molecule and the 5 amino acids residues KGDFR located in the binding region of the angiotensin converting enzyme 2 ACE2 molecule, a receptor for the spike glycoprotein on the virion surface of SRAS CoV 2, between humans, dogs, cats, tiger and other mammals. Although the transmission of human coronavirus to pets or animals is rare, the dangers of transmitting SARS CoV 2 from animals or pets to humans have not been proven. Our findings with Shi’s study provide important insights into the animal models for SARS CoV 2 and animal management for COVID 19 control. ACE2, SARS CoV 2, COVID 19, binding region 274-276 Issue-4 Volume-4 Takuma Hayashi | Masaki Mandan | Nobuo Yaegashi | Ikuo Konishi