Ship length of VLCC is long compared with sea wave length. Hydrodynamic pressures on a full ship in short waves are measured to investigate the wave loads of VLCC. The predicted hydrodynamic pressure distributions at some sections with New Strip Method (NSM) and 3 Dimensional Source Sink Method (3DM) are compared with the measured ones. The predicted results with NSM are not in good agreement with the measured ones in short waves. But, the predicted results with NSM with longitudinal cut are in good agreement with the measured ones only in short waves and the predicted results with 3DM are in good agreement with the measured ones in whole wave frequencies. From the above results, it is found that the diffracted wave from the bow and the bottom is important term to estimate the wave loads and the hydrodynamic pressures in short waves. These diffracted waves are not taken into consideration for the strip method. The modified method for the diffracted wave term of NSM is developed with the diffracted waves calculated with 3DM for the ships with different length beam ratios. The predicted pressure distributions with this modified method for NSM are in good agreement with the measured pressure distributions in whole wave frequencies.