As the International Maritime Organization (IMO) recently introduced the Energy Efficiency Design Index (EEDI) for new ship buildings and the Energy Efficiency Operational Indicator (EEOI) for ship operations, thus an accurate estimation of added resistance of ships advancing in waves has become necessary. In the present study, OpenFOAM, computational fluid dynamics libraries of which source codes are open to the public, was used to predict the added resistance and motions of a ship. Unstructured grid using a hanging-node and cut-cell method was used to generate find grid around a free-surface and ship. A dynamic deformation mesh method was used to simulate the motions of the ship. Five wave lengths from a short wave length (λ/LPP=0.65) to a long wave length (λ/LPP=1.95) were considered as head waves. The grid uncertainty was evaluated with respect to three grid systems for a wave length of λ/LPP=1.15. The predicted added resistance, and heave and pitch motions with various head waves were compared with the data of model experiments. The wave pattern around the ship and motions of the ship analyzed with respect to individual waves.