Neuroblastomas are embryonal tumors arising from the neuronal crest cells of the synaptic nervous system. Findings from aspiration cytology have been reported, but there have been no reports of urine cytology findings. Here, we report a case of pediatric neuroblastoma characterized by urine cytology. A 2-year-old boy presented with abdominal pain, nausea, and loss of appetite. Computed tomography revealed a large tumor in the left suprarenal region with massive infiltration into the kidney. Urinary cytology showed highly cellular clusters composed of small, round, atypical cells with little cytoplasm and high nuclear/cytoplasmic ratio; nuclear molding was also noted in some places. Immunocytochemical staining was positive for synaptophysin and chromogranin A, and neuroblastoma was suggested by urine cytology. A biopsy of the left adrenal tumor later confirmed a diagnosis of poorly differentiated neuroblastoma. Urine cytology may be useful for rapid diagnosis and management of similar cases.