The novel coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 remains a major global crisis and continues to spread relentlessly around the world. In Japan, the number of infected people has incrementally increased since April 2020. The COVID-19 pandemic has exerted a major impact not only on our daily lives but also on healthcare. As the infection continues to spread, many medical institutions have devoted all efforts to minimize the risk of infection not only for patients but also for medical personnel by prioritizing medical care, reserving treatment, and extending consultation intervals. Cancer treatment is one of the priorities for medical care even during an epidemic infection as there is a concern of decreasing curability or therapeutic effect from postponement. As the COVID-19 situation evolves rapidly, we created an informative triage to provide appropriate medical treatment to breast cancer patients. In this triage, we offer guidance on preparing for the impact of the COVID-19 pandemic in breast cancer patients, prioritizing triage and diagnostic procedures, and providing advice on surgical, radiation, and oncological treatments.