This paper deals with the prediction of propeller cavitation noise both from model experiments in a cavitation tunnel and from a theoretical calculation along with its comparison with full scale measurements for two ships, a cargo liner and a training ship. It is proposed to estimate separately blade rate tones and broadband noise both in model experiment and theoretical calculation considering the different noise-generation mechanisms. In model experiment, the acoustical-mechanical reciprocity technique is applied for the estimate of blade rate tones and a theoretical estimate formula supports the experimental prediction of low-frequency broadband noise. Full scale measurements of far-field noise are carefully planned to get reliable data so as for example to get rid of the effects of sound reflection at the sea surface. The comparisons between predictions and full scale measurements show reasonable agreements.