PURPOSE: To improve the efficiency of recovery work in the case of a work vessel for collecting oil run out to the sea or the like by providing inside or outside ship shells oil collection tanks having side walls higher than the water line and bottom surfaces deeper than an oil collection border line, opening an oil collection opening in the vicinity of the oil water border line of a side wall.

CONSTITUTION: The primary oil collection tank 2 and the secondary oil collection tank 3 are provided extending over the paired right and left ship shells 1a, 1b and the outside of a ship shell 1 in the middle of ship shells 1a, 1b. The primary oil collection tank 2 is composed of side walls 2a whose upper edges are at higher positions than that of the water line, and a bottom surface 2b deeper than an oil collection border line that is lower than the water line WL. And, oil is taken into the primary oil collection tank 2 by forming an oil collection opening 4 at a position in the vicinity of an oil water border line OL at a side wall 2a. Both oil collection tanks 2, 3 are connected to each other by means of oil passing pipes 11 at positions lower than the oil water border line OL and by means of a water passing pipe 12 at a position near a bottom surface 2c. Near the bottom of the secondary oil collection tank 3, a draining device 14 is connected.