PURPOSE: To improve a crossing part between a longitudinal and a cross beam, in a ship body structure.

CONSTITUTION: In a crossing part between a longitudinal 1 and a cross beam 2 welded to a ship body shell plate 3, the longitudinal 1 is arranged so as to separate from a U-shaped slot internal periphery of the cross beam 2, and a bracket 5 of almost isosceles triangular shape for connecting the longitudinal 1 to the cross beam 2 is provided. A slot upper edge part of the cross beam 2 is welded to be fitted to cross with a cut groove 5a along a top angle bisector of the bracket 5, and a bottom side of this bracket 5 is welded to a face bar 1a of the longitudinal 1.