We report a 3-month-old male with infantile hypophosphatasia who later developed Pseudotumor cerebri. At the age of 3 months, he was referred to our hospital because of pneumonia and respiratory insufficiency. He had short extremities, and radiographs of the bones were consistent with lack of metaphyseal mineralization and bowed lower extremities. Vomiting and bulging fontanelle developed 3 months after admission, and CSF opening pressure was notably high at 430 mm/H2O. Hypophosphatasia is a very rare cause of pseudotumor cerebri. This report is the first case where PTC is associated with hypophosphatasia and responded well to corticosteroid therapy.