The patient was 57 years old when he was diagnosed with amyotrophic lateral sclerosis (ALS) at 1 year after developing bulbar symptoms. At 58 years old, he stated that he was considering donating his kidney to his son suffering from diabetic nephropathy. We confirmed the patient's intentions through repeated interviews before his death at 61 years old. Nephrectomy was performed 30 min after his cardiac death. Organ donation spontaneously proposed by an ALS patient should be considered in order to meet the requests of patients who want their families and other patients to live longer, thereby imparting a beneficial legacy through their deaths.