The result of theoretical and experimental studies on the longitudinal vibration of the four cylinder longstroke engine installed in the 34000 dwt bulk carrier is shown in this paper as a continuation of 1st report. In these studies, it is shown that the longitudinal engine vibration has such a characteristics of soft spring system that the frequency decreases with the increased amplitude and the engine top bracing to restrict the vibration amplitude has a possibility to excite the vibration of the ship structure. In addition the longitudinal engine vibration is considered to be excited by the fluctuating thrust force originated from the longitudinal shaft vibration coupled with the torsional shaft vibration.