We report a case of paratesticular rhabdomyosarcoma in a one-year and nine-months old male infant. The patient presented with an asymptomatic enlargement of the right scrotum. Ultrasonography indicated a solid mass 3 cm in size in the right scrotum. Computed tomography and magnetic resonance imaging revealed a right testicular tumor with no distant metastases. Serum lactate dehydrogenase, human chorionic gonadotrophin beta, and alpha-fetoprotein were within normal limits. Although surgical treatment was scheduled based on the diagnosis of the testicular tumor, the patient had a high fever with a viral infection, and the surgery was postponed. The tumor rapidly progressed to 7 cm in size within one month. High orchiectomy was performed, and histopathological examination confirmed a paratesticular rhabdomyosarcoma. The patient received adjuvant chemotherapy with vincristine sulfate, actinomycin D, and cyclophosphamide. There was no recurrence one year post-surgery. Paratesticular rhabdomyosarcoma commonly occurs in the paratesticular tissues of pediatric patients. This case highlights the importance of the differential diagnosis of paratesticular rhabdomyosarcoma other than testicular tumor for painless scrotal masses in infants and the requirement for multidisciplinary management in pediatrics.