Following the first case of Coronavirus Disease 2019 (COVID-19), caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-Cov-2), in Wuhan, China, in December 2019, it has spread worldwide. An outbreak in Japan occurred on a cruise ship, and this was followed by community-acquired COVID-19. Herein, we report three cases of COVID-19 that presented pneumonia following admission to Kitasato University Hospital. Patients were admitted based on the positive result of real-time reverse transcriptase-polymerase chain reaction (RT-PCR) tests for COVID-19 nucleic acid. All patients were diagnosed as suffering from non-severe COVID-19 pneumonia and were successfully treated with Lopinavir/Ritonavir (LPV/r). LPV/r could be an option for treating non-severe COVID-19 pneumonia in general and even in elderly patients.