Since the first case of COVID-19 was reported from Wuhan, China in December 2019, SARS-CoV-2 has been spreading globally and has become major public health concern. At present, development of specific treatment for COVID-19 is in progress and several countermeasures have been subjected to clinical trials. However, efficacy of these countermeasures is limited. For development of effective medicines or vaccines against infectious diseases, it is mandatory to elucidate its etiology and pathogenesis by means of pathological analysis. Pathological studies revealed that the COVID-19 mainly affects respiratory tracts although other organs are also involved. In addition, immunological studies demonstrated that host immune response may exacerbates COVID-19 through systemic inflammation. In this review, we would like to overview pathology and immunology of COVID-19.