A 78-year-old Japanese woman presented with anemia. Oral double-balloon endoscopy (DBE) detected multiple ulcerative lesions covered with coagula extending up to approximately 20 cm from the mid-jejunum. Based on the histopathological findings, the patient's condition was diagnosed as mucosa-associated lymphoid tissue (MALT) lymphoma of the small intestine. During the second DBE examination, a small intestinal perforation occurred in one of the ulcerative lesions, and an emergency segmental small intestinal resection was performed. The present case suggests that in MALT lymphoma, intestinal wall fragility may lead to perforation even though the lesion may appear to be a superficial ulcer on endoscopy.