PURPOSE: To prevent the intrusion of rain water reliably, by opening an exhaust tube of an engine room to the rear end of a stern deck while covering it with a member of a reverse U-shape extending across the sides of a vessel.

CONSTITUTION: The exhaust gas from an exhaust tube 6 provided on a stern deck 1 is fed to a covering member 3 extending across the sides of a vessel, where the rain water is blocked by said member 3 and never intrude into said tube 6 thereby even if the wave is thrown over the stern at the backing to intrude a portion into an opening 30, it is blocked by a fixing member 8 to block the intrusion into the exhaust tube 6. Since the covering member 3 is extending laterally to provide a step at the stern, it causes no trouble for the work on the deck.