Coronavirus disease 2019 (COVID-19) vaccination is reportedly safe and effective. The histologic features of post-COVID-19 vaccination myocarditis are unknown. We present a 77-year-old Japanese woman who was diagnosed with eosinophilic myocarditis using endomyocardial biopsy, 7 days after receiving the second dose of BNT162b2 COVID-19 vaccine. Methylprednisolone pulse therapy was effective.