A 68-year-old man was admitted to our hospital with complaints of fatigue, polyuria, and loss of appetite, and was diagnosed with diabetic ketosis. Chest and abdominal computed tomography (CT) showed a pulmonary tumor on the right S3 and multiple liver tumors. Blood chemistry revealed elevated levels of amylase and hepatobiliary enzymes. Pathological examination of a biopsy specimen from the liver tumor showed a small cell carcinoma. Based on the imaging and pathological findings, we made a diagnosis of extensive disease small-cell lung cancer (ED-SCLC), cT1aN3M1b (HEP, ADR). Treatment with carboplatin and etoposide evoked partial response and the serum level of amylase decreased. Immunohistochemical staining of liver biopsy specimen was positive for amylase, leading to a diagnosis of SCLC with amylase production. About 22 months after the diagnosis of SCLC, he was admitted to our hospital with fatigue, muscular weakness, edema, and hyperpigmentation. Laboratory findings showed elevated serum levels of hepatobiliary enzymes, adrenocorticotropic hormone (ACTH), and cortisol, and a decreased serum potassium level. Urinary potassium level was elevated. Pituitary magnetic resonance imaging showed a normal morphology. We made a diagnosis of SCLC complicated by Cushing’s syndrome. We report this rare case of SCLC with amylase and ACTH production, which was detected in the course of treatment of SCLC.