Results of numerical and experimental study are presented of the wave forces acting on a blunt ship advancing in oblique waves. A 3-D panel method using a new numerical scheme proposed one of the present authors for evaluating the Green function was applied to numerical estimation of wave forces in short waves provided that the line integral and the steady disturbance on the body surface can be neglected, and the numerical results are compared with the experimental ones in full detail. The effect of the number of discretized panels on the body surface is investigated by increasing the number of panels from about 400 to 1600 and it is confirmed that the number of panels affects significantly accuracy of computed second order steady forces but the effect is not so remarkable on the first order wave forces. Two different descriptions of the wave term of the Green function, one is the monopole type and the other is the panel type obtained by integrating analytically the monopole over the panel, are also investigated. We confirm that as large number of panels as the monopole type is necessary to obtain the accurate solutions even if the panel type estimation is adopted. The present study confirmed that 3-D panel method is useful to predict the wave forces comparative-ly in long waves, while in short waves it does not give such accurate solutions as be in good agreement with experiments even if the large number of panels is used.