Introduction: Patients with motor neuron diseases, such as amyotrophic lateral sclerosis (ALS), have higher sensitivity to nondepolarizing neuromuscular blocking agents (NMBAs) and are at higher risk for a residual block. For this reason, the use of NMBAs such as rocuronium has been limited owing to the delayed reversal of muscle relaxation. It was recently reported that rapid and effective reversal of muscle relaxation occurs when sugammadex, a muscle relaxant reversal drug, is administered to patients in ALS with rocuronium-induced muscle relaxation. However, in this paper, we report the incomplete recovery and recurarization of muscle relaxation after sugammadex administration in ALS patients, and delayed recovery of muscle relaxation after additional administration of sugammadex. Patient concerns: A 71-year-old male patient with ALS received general anesthesia for laparoscopic nephroureterectomy. Diagnosis: The patient was diagnosed with ALS 2 years earlier, and scheduled to undergo laparoscopic nephroureterectomy for ureteral cancer. Intervention: We used sugammadex for the reversal of deep neuromuscular block. We measured a train-of-four (TOF) count of 4 and a TOF ratio of 54% at about 8 min after administration of 4 mg/kg sugammadex. However, then the TOF count decreased to 1 to 3 and tidal volume (TV) decreased to < 100 mL. Therefore, an additional 50 mg sugammadex was administered intravenously 12 min after the first dose of sugammadex was injected. Outcomes: The patient's vital signs were stable and his recovery from anesthesia was uneventful. Therefore, he was discharged to the intensive care unit. The patient had aspiration pneumonia symptoms owing to dysphagia on the third postoperative day, but after the symptoms improved he was transferred to the hospital for rehabilitation of dysphagia and dyspnea. Conclusion: It is critical to monitor whether muscle relaxation is sufficiently reversed when using sugammadex in ALS patients. Further research is needed to determine the appropriate dose of sugammadex for muscle relaxation reversal.