PURPOSE: To both obtain effective use of a space in a ship side part and facilitate work of manufacturing a ship body, by cutting both side parts of a deck in an upper structure of double skin type formed as an integral unit, water-tightly connecting it directly to the ship side and mounting a gunnel part of different unit to the upper part of the above.

CONSTITUTION: In manufacture of a ship made by fiber reinforced plastics (FRP) of so-called double skin type where its upper structural whole body is formed as an integral unit to cover an integrally formed ship body and connect a peripheral edge part, a gunnel 6 for covering the peripheral edge part of a lower part ship body is not formed in a deck member 3 at both side parts of a cockpit and an edge part 30 of the deck member is water-tightly connected directly to a ship side 10 by cutting the deck member 3. A gunnel part 8 of different unit is mounted to the upper part of the above in such a manner as to be in a continuous state to the gunnel 6 in front and rear parts, and a partition plate 9 is jointed to use the ship side part for a storeroom and drain device and both obtain effective use of a space in the ship and facilitate its manufacture.