To provide a sea chest structure in a ship which is capable of eliminating a non-uniform pressure distribution generated at an inlet part to suck water.

In a sea chest structure which is formed in a hull bottom part 1 and suck water for water jet, a plurality of through-holes 4 are formed in the vertical direction in a downstream lip part 3 of a sea chest 2, and the movement of a stagnation point generated when the IVR (the ship speed-to-flow speed ratio) during the navigation is different from the design IVR is returned to a tip of the lip part 3 by communicating upper and lower surfaces of the lip part 3 with each other.