An 86-year-old man was diagnosed with bulbar type of amyotrophic lateral sclerosis (ALS). He underwent a bumper-tube type of gastrostomy due to dysphagia 16 months after the onset of ALS. Twenty months after the onset, he developed dyspnea due to anemia. Upper gastrointestinal endoscopy showed a gastric ulcer contralateral to the gastrostomy site with bumper indentation from the gastrostomy tube. Patients with ALS might develop gastric ulceration due to mechanical stimulation with a percutaneous endoscopic gastrostomy tube.