BACKGROUND: While many studies have verified the effect of recent anti-cancer treatment in patients with COVID-19, there are no data on the optimal time for cancer treatment resumption, as well as the safety of chemotherapy in COVID-19 patients. As many cancer patients are recovering from COVID-19, there is an urgent need for reliable clinical information. Herein, we report a case of invasive ductal carcinoma in which we were able to successfully resume chemotherapy after infection with SAR-CoV-2. CASE PRESENTATION: The patient was a 38-year-old non-smoking Japanese woman with no significant medical history. She had fever on days 5 and 6 of her second course of adjuvant FEC therapy, and on day 7, she tested positive for SARS-CoV-2 by RT-PCR. She was hospitalized for 11 days. We resumed the therapy on day 25 after discharge, as she had no remaining clinical symptoms. The patient completed four courses of the initial chemotherapy without any major adverse events nor the recurrence of COVID-19, and subsequently completed four courses of docetaxel as her second regimen therapy. CONCLUSIONS: Evaluating the risk for each patient is essential when resuming anti-cancer therapy in cancer patient's post-COVID-19.