To facilitate passage on an upper deck of an oil tanker by eliminating various pipes such as a cargo oil pipe from the upper deck of the oil tanker.

Pipe lines 42 having a sealed structure of a substantially rectangular section are formed in the upper portion of a central cargo oil bath 34 of an ore/oil carrying vessel to be interposed between vertical bulkheads 32 and a hatch 38. Two of cargo oil delivery pipes 50 leading from a pump chamber toward a shore connection 48 of the central portion of a hull extend through the starboard pipe line, and the remaining one extends through the larboard pipe line. The starboard pipe lines extend up to the hull center portion, but the larboard pipe line extends so long as the bow, and an inert gas pipe 58 is threaded in the larboard line.