In a ship including a single screw vessel type stem equipped with overlapping propellers, a waterline shape of a stem S in an area of at least 0.4R (R denotes a propeller radius) in a vertical direction from shaft centers of propellers 1 and 2 is formed such that an inclination angle ± of an aft end portion of the waterline is 15 degrees or smaller with respect to a hull centerline, and a virtual width at an aft end position is 600 mm or smaller when the waterline shape is extended to an aft end. Further, a bracket fin 8 may be provided in a space between each of stem tubes 3a and 4a into which propeller shafts 3 and 4 are respectively inserted and the stem S. Moreover, a wake improved fin 13 for improving a wake distribution which is accelerated by the rotation of the fore propeller 2 and flows into the aft propeller 1 is provided above the propeller shafts 3 and 4 and at the stem S.