A new method to estimate the directional wave spectra from motions of a ship running in the directional seas is developed in this paper. The method is constructed based on the Parametric Method assuming the linearity between incident waves and motions of a running ship. The accuracy of the present method is investigatd by numerical simulations and is shown to resolve different directional seas consistently from motions of a running ship, particularly in the following sea condition. The method is also used to analyze experimental data obtained from a free-running test of a VLCC model and is shown to be a powerful tool for the directional wave estimation from motion of a running ship.