Sugammadex 4 mg·kg⁻¹ is recommended for reversal from rocuronium-induced deep neuromuscular block. However, there is limited data regarding the dose-response of sugammadex required for reversal from deep neuromuscular block in pediatric patients. The aim of this study was to determine the reversibility of rocuronium-induced deep neuromuscular block with sugammadex in infants and children. Seventy-five children (48 infants and 27 children, mean standard deviation (S.D.), age: 11.6 (6.7) months) were enrolled in this study. After induction of anesthesia and administration of 0.6 mg·kg⁻¹ rocuronium, neuromuscular block was acceleromyographically evaluated by observing contractions of the adductor pollicis muscle to ulnar nerve train-of-four (TOF) stimulation. Subsequently, the intensity of rocuronium-induced block was determined every 6 min using post-tetanic count (PTC) stimulation during sevoflurane and remifentanil anesthesia. When the first response to the PTC stimulus was detected, either 1, 2 or 4 mg·kg⁻¹ sugammadex was administered and the time required for facilitated recovery to a TOF ratio of 0.9 following each dose was compared. The time [mean (S.D.)] from the administration of 1 mg·kg⁻¹ sugammadex until recovery to a TOF ratio of 0.9 was significantly longer [129.1 (83.5) s, p < 0.001] than that with 2 and 4 mg·kg⁻¹ sugammadex [70.3 (26.7) s and 68.2 (34.5) s, respectively]. Incomplete reversal was seen in 3 patients in the 1 mg·kg⁻¹ group. The results suggested that a 4 mg·kg⁻¹ sugammadex dose is recommended for reversal from rocuronium-induced deep neuromuscular block even in infants and children.