PURPOSE: To provide an attitude control device for a ship wherein generation of a bow trim and useless increase of resistance in a sailing condition can be prevented while heel control can be easily performed by even a beginner.

CONSTITUTION: Respective operating regions of flap plates 3R, 3L are plurally divided to provide a flap controller(flap control means) 6 for determining to preferentially swivel any of the flap plates 3R, 3L in accordance with at least positions thereof. Since the flap plates 3R, 3L are operated in accordance with the predetermined order of priority by on-action of an operating switch 15 in no relation to intention of a crew, operation by the crew is simplified, and heel control can be easily performed by even a beginner. Generation of the situation, where both the flap plates 3R, 3L are concentrated downward, is avoided to prevent generation of a bow trim and useless increase of resistance in a sailing condition.