Purpose: The development of assistive devices has allowed for the performance of capsule endoscopy in children. Anticipating the capsule’s transit time could affect the efficacy of the investigation and potentially minimize the fasting period. This study determined the predictors of small bowel transit time for small-bowel capsule endoscopy in children and adolescents with inflammatory bowel disease. Methods: We retrospectively examined children and adolescents with inflammatory bowel disease who underwent capsule endoscopy by the age 18 at a Japanese tertiary care children’s hospital. Small bowel transit time predictors were analyzed using multiple regression with explanatory variables. Results: Overall, 92 patients, aged 1–17 years, with inflammatory bowel disease (63 Crohn’s disease and 29 ulcerative colitis cases) were examined for factors affecting small bowel transit time. In the simple regression analysis, diagnosis, age, height, weight, serum albumin, general anesthesia, and small intestine lesions were significantly associated with small bowel transit time. In the multiple regression analyses, serum albumin (partial regression coefficient: −58.9, p=0.008), general anesthesia (partial regression coefficient: 127, p<0.001), and small intestine lesions (partial regression coefficient: 30.1, p=0.037) showed significant associations with small bowel transit time. Conclusion Hypoalbuminemia, the use of general anesthesia for endoscopic delivery of the capsule, and small intestine lesions appeared to be predictors of prolonged small bowel transit time in children and adolescents with inflammatory bowel disease. Expecting the finishing time may improve examination with a fasting period reduction, which benefits both patients and caregivers.