Background: Pyriform sinus fistula, congenital anomaly originating from the third or fourth brachial pouch remnant, rarely occurs during the prenatal period. Case Report: A pregnant woman was referred to our hospital at 30 weeks of gestation with ultrasonographic finding of fetal cervical cyst. Fetal ultrasonography had revealed a left unilocular cystic lesion in neck.. Although it remained unchanged in size, deviation of the trachea by the cyst was later demonstrated by magnetic resonance imaging. A male child was born with a good Apgar score by elective cesarean delivery. Mild respiratory dysfunction was resolved by immediate cyst aspiration. Our diagnosis was pyriform sinus fistula with subcutaneous cyst formation based on catheterization performed under laryngoscopy. Our hospital pediatric surgeons removed the cyst and fistula, and the post-operative course was uneventful. Conclusion: The possibility of pyriform sinus fisuta must be kept in mind for fetal cystic lesions of neck.