Although the link between pulmonary arterial hypertension (PAH) and exposure to certain drugs has already been identified, we herein present the first case of herbal medicine-associated PAH in which the patient demonstrated spontaneous remission. A 38-year-old woman took the herbal medicine "bofutsushosan" for two weeks then stopped taking it due to exertional dyspnea. However, her dyspnea continued, and right heart catheterization revealed a mean pulmonary arterial pressure of 41 mmHg with a normal wedge pressure. Several months after treatment with oxygen therapy, the patient's dyspnea disappeared, and her pulmonary arterial pressure normalized. Further studies focusing on susceptibility factors to drug-induced pulmonary arterial hypertension are needed.