A coating apparatus wherein the coating is made by a coater while a support is carried in a non-contacting manner by a gas jetted from a gas jetting device towards the support. The gas jetting device has a hollow housing into which the gas is introduced from a gas source, the wall of the housing adjacent to the support being provided with a plurality of gas jetting nozzle ports through which the gas is jetted towards the support, each gas jetting nozzle port having a throat portion presenting a minimum cross-sectional area inwardly spaced from the outer surface of the wall of the housing and an enlarged outlet portion presenting a comparatively large diameter and opening in surface of the wall. The ratio of port area is adjusted in such a manner that the rate of jetting of the gas from unit area of the outer surface of the gas jetting device becomes smaller as the width of the support is increased.
