A gas wiping apparatus for use in coating a molten metal onto a steel strip. In the apparatus, a chamber, to which a high pressure gas is supplied, defines a multistage uniform pressure space. A lip support unit is associated with a front of the chamber to allow the high pressure gas to flow therethrough, the lip support unit supporting the apparatus against load. Upper and lower lips are associated with a front of the lip support unit to cooperatively define an outlet. The upper lip adjusts a gap of a gas outlet cooperatively with the lower lip, and can be easily installed in a lip support unit while adjusting the gap of the gas outlet stably. Also, edge over coating (EOC) of the steel strip can be prevented without an additional auxiliary nozzle.