The cavitation erosion behavior of wear resistant hardfacing alloys, Fe-base NOREM 02, Ni-base Deloro 50 and Co-base Stellite 6, were investigated up to 30hrs using a 20kHz vibratory apparatus. It was shown that the mean erosion depths of Stellite 6. NOREM 02 and Deloro 50 after 30hrs test were 15㎛, 37㎛ and 75㎛, respectively and the nominal incubation time of both NOREM 02 and Deloro 50 were about 1hr while it was about 8hrs for Stellite 6. It is considered that the lower cavitation erosion resistance of NOREM 02 than Stellite 6 is mainly due to the undevelopment of the strain-induced phase transformation. It was also considered that the lowest cavitation erosion resistance of Deloro 50 among the three hardfacing alloys is due to the easy formation of cracks at the interface between matrix and hard second phase as well as the high stacking fault energy of Ni-base matrix.