To facilitate the maintenance of an upper deck aggregate, reduce the burden of a steel material amount and also reduce a mooring outer force and improve a cleaning efficiency by making the reinforcement material of the upper deck installed on the upperside of the upper deck of a hull to a stand and loading a process module on its upper part.

The reinforcement material for supporting the upper deck of FPSO(floating.production.storage and off-loading unit) ship is mainly the aggregate of a longitudinal (vertical) direction (longe material 1) and the aggregate of a width (horizontal) direction (trans material 4). Both longe material 1 and trans material 4 are installed to the outboard of upperside of the upper deck. At the case of FPSO for LPG, it is favorable that especially the trans material 4 which is the aggregate of the width direction is installed on the upperside of the upper deck. Thereby, the maintenance of the aggregate of the upper deck becomes easy and the burden of a steel material amount can be reduced and also a mooring outer force is reduced and a cleaning efficiency is improved by the shrinkage of a hull size.