Cavitation-erosion tests of steel, coated with a layer of titanium nitride (TiN) by physical vapor deposition, were conducted using a wall-facing vibratory testing facility and an ultrasonic cavitation-erbsion testing facility based on the ASTM Method for Vibratory Cavitation Erosion Test (G 32-85). The amount of erosion damage to the test specimen was evaluated by various methods. It was confirmed that the erosion resistance of TiN coated steel is superior to steel coated with the same film thickness of electroplated chromium, and of course to uncoated base metal (SUS410J1 stainless steel). It has been also confirmed that chromium-titanium nitride multilayered coating shows the most effective erosion resistance among the tested ion-plated coating specimens. The reasons of this improvement in the erosion resistance of TiN coated materials are as follows. First, the TiN layer did not peel off from the substrate surface, owing to its adhesion strength. Secondly, the erosion resistance of the layer itself was greater than that of the substrate material. In addition, it has been confirmed that this erosion resistance is maintained even after the erosion damage has reached the substrate material, since the residual stress generated by the layer deposition improves the durability of the base metal.