A 76-year-old woman was referred to our hospital with anorexia. Computed tomography revealed a tumor lesion measuring 110mm in the liver at S4/5 with calcification and swelling of a paraaortic lymph node. The gallbladder was not visualized. Histological examination of a biopsy specimen from the liver tumor revealed squamous cell and undifferentiated carcinomas, and several tumor markers were elevated. Therefore, we diagnosed the patient with gallbladder adenosquamous cell carcinoma T3N2M0 stage III. Because the serum parathyroid hormone-related protein (PTHrP) and granulocyte-colony stimulating factor (G-CSF) levels were significantly elevated, we suspected that PTHrP and G-CSF production occurred because of adenosquamous cell carcinoma in the gallbladder. We initiated chemotherapy with S-1.