A case of invasive thymoma associated with pure red cell aplasia and liver metastasis was reported. A 57-year-old male was admitted to our hospital because of hepatic abnormal shadow on computed tomography. Malignant tumor was suspected by imaging procedures. Left lateral segmental resection of liver was performed and histo-pathological examination proved the tumor to be liver metastasis of thymoma. He was received 50 Gy irradiation after incomplete resection of thymoma. In the course of time he contracted pure red cell aplasia. But he is well controlled medically and alive 7 years after the surgery.