Hereditary stomatocytosis is an autosomal dominant, congenital hemolytic form of anemia, and thromboembolic complications may ensue after a splenectomy is performed in a patient with hereditary stomatocytosis. However, little is known about the relationship between pulmonary hypertension and hereditary stomatocytosis. We describe here a rare case of a patient with hereditary stomatocytosis who developed pulmonary hypertension due to thromboembolic disease after splenectomy. At the first presentation, he was diagnosed with hemolytic anemia, but the cause was unknown, and he was also diagnosed with pulmonary hypertension. Thereafter, we linked his pulmonary hypertension with hemolytic anemia because his red blood cells appeared as leptocytes, acanthytes, and stomatocytes on scanning electron microscopy. It is important to confirm the diagnosis of hemolytic anemia, and splenectomy should be performed with due consideration of whether patients have hemolytic anemia.