Amyloidosis is characterized by the abnormal deposition of extracellular amyloid fibrils. Cases involving amyloid light-chain amyloidosis in the small intestine have been reported infrequently in Korea. Here, we report a case of localized light chain protein amyloidosis in the small intestine. Esophagogastroduodenoscopy, push enteroscopy, and capsule endoscopy revealed submucosal tumor-like lesions, multiple shallow ulcers, and several erosions in the distal duodenum and jejunum. An endoscopic biopsy established the diagnosis of amyloidosis. In through an immunohistochemical analysis, the presence of lambda light chain protein was detected. The patient had no evidence of an underlying clonal plasma cell disorder or additional organ involvement. Therefore, we concluded that the patient had localized amyloidosis of the small intestine.