Infantile hypertrophic pyloric stenosis (IHPS) is one of the common surgical abdomen in infancy, characterized by progressive non-bilious vomiting. The etiology is unknown, but it likely develops after birth. The pylorus of the stomach becomes thick and triggers progressive vomiting. Abdominal ultrasonography (US) is widely used as a diagnostic tool. Currently, there is a rare IHPS patient with severe metabolic derangement because of general use of abdominal US and its accuracy. We experienced a natural course of a 62- day-old male infant with IHPS who was suffering from intermittent vomiting, loss of weight but had not been properly treated for 1 month. It is needed to make an effort to diagnose differentially in recurrent vomiting infant and check-up regularly, and also educate parents properly.