In the 1st and 2nd reports, direct formulation of boundary element method (BEM) based on the thick wing theory to the analysis of three-dimensional flow around the marine propeller in uniform flow and in steady ship's wake has been successfully presented. In the present paper, the accuracy of BEM analysis to the three-dimensional flow around marine propeller is examined by the pressure distributions measurement of six kinds of model propeller blade. After comparison BEM calculated pressure distributions with measured ones, it is verified that the BEM analysis by direct formulation to the three dimensional flow around marine propeller is very usefull.