In the ultrasonic atomization, the contribution of evaporation to the rate of accompanying liquid was examined. Pure water was used as the liquid to be atomized and nitrogen was used as the carrier gas to accompany the atomized droplets. The velocity, the humidity (dry or wet) and the outlet height of carrier gas were changed, and the rate of accompanying liquid was measured. The evaporation rate increased with increasing gas velocity but was unchanged at the higher gas velocity. The evaporation rate was higher at the high outlet of carrier gas than at the low one. The contribution of evaporation became smaller with increasing gas velocity.