PURPOSE: To prevent heat from being transmitted from an engine room to a fish hold, by forming a bulkhead between the engine room and the fish hold in a double-walled structure, and as well by providing openings for a deck and the engine room in the upper and lower sections of the double-wall structure bulkhead.

CONSTITUTION: In a fishing ship made FRP and provided with a ship hold 3 before an engine room 2, the bulkhead 5 between the engine room 2 and the fish hold 3 is formed of double walls 6, 7. An opening 70 opened to a position above a deck 8 is formed in the upper part of the front side wall 7 of these double walls, and an opening 70 opened to the engine room 2 is formed in the lower part of the rear side wall 6. By passing ventilating air for the engine room 2 through the space between double walls 6, 7 heat may be prevented from being transmitted from the engine room to the fish hold with no special insulator being used.