We presented a case of posteriorly displaced fracture of the distal clavicle in Child. The closed reduction was failed due to posteriorly displaced proximal fragment and interpositon of trapezius muscle and periosteum. We found that periosteal sleeve and coracoclaviclar ligament and acromioclavicular ligament was intact. The open reduction should be considered for the treatment of the irreducible posteriorly displaced fracture of the distal clavicle in child.