A 91-year-old man hospitalized with pneumonia was referred to our department due to sudden massive fresh hematochezia on the 13th day of hospitalization. At admission, a right femoral neck fracture was also found and required bed-rest as a nonoperative treatment. He had a history of pneumonia and hypertension. He had smoked 2 packs-per-day of cigarettes for over 30 years but quit 40 years ago and was a social drinker. His family history was unremarkable. He presented signs of hypovolemic shock with low blood pressure (BP of 79/38 mmHg) and tachycardia (101 bpm). The vital signs were stabilized after a rapid infusion of 1000 mL of lactated Ringer’s solution. His abdominal examination was normal with no tenderness. His hemoglobin level dropped from 11.5 to 7.2 g/dL. Contrast computed tomography revealed extravasation in the lower rectum. After computed tomography, we promptly performed an emergent colonoscopy using a prototype endoscope (GIF-Y0058; Olympus Co., Tokyo, Japan) instrumented with RDI mode, and an ulcer accompanied with a pulsatile bleeding was found on the lower rectum.