A method for controlling posture of a marine vessel with posture control tabs mounted on a stern of a hull of the marine vessel to control a posture of the hull , and actuators to actuate the posture control tabs , the method comprises judging whether or not the hull is being loaded onto a trailer on a basis of a speed of the hull and a pitch angle of the hull , or judging whether or not the hull is being loaded onto a trailer on a basis of a number of engine revolutions of a propulsion device including an engine to generate a propulsive force to move the hull and a speed of the hull , or judging whether or not the hull is being loaded onto a trailer on a basis of a throttle opening angle of a propulsion device including an engine to generate a propulsive force to move the hull and a speed of the hull , or judging whether or not the hull is being loaded onto a trailer on a basis of an acceleration of the hull and a pitch angle of the hull , or judging whether or not the hull is being loaded onto a trailer on a basis of a number of engine revolutions of a propulsion device including an engine to generate a propulsive force to move the hull and an acceleration of the hull , or judging whether or not the hull is being loaded onto a trailer on a basis of a throttle opening angle of a propulsion device including an engine to generate a propulsive force to move the hull and an acceleration of the hull , or judging whether or not the hull is being loaded onto a trailer on a basis of a throttle opening angle of a propulsion device including an engine to generate a propulsive force to move the hull and a pitch angle of the hull , or judging whether or not the hull is being loaded onto a trailer on a basis of a number of engine revolutions of a propulsion device including an engine to generate a propulsive force to move the hull and a pitch angle of the hull ; and, upon judging that the hull is being loaded onto the trailer , controlling the actuators to position the posture control tabs at retracted positions. judging whether or not the hull is being loaded onto a trailer on a basis of a speed of the hull and a pitch angle of the hull , or judging whether or not the hull is being loaded onto a trailer on a basis of a number of engine revolutions of a propulsion device including an engine to generate a propulsive force to move the hull and a speed of the hull , or judging whether or not the hull is being loaded onto a trailer on a basis of a throttle opening angle of a propulsion device including an engine to generate a propulsive force to move the hull and a speed of the hull , or judging whether or not the hull is being loaded onto a trailer on a basis of an acceleration of the hull and a pitch angle of the hull , or judging whether or not the hull is being loaded onto a trailer on a basis of a number of engine revolutions of a propulsion device including an engine to generate a propulsive force to move the hull and an acceleration of the hull , or judging whether or not the hull is being loaded onto a trailer on a basis of a throttle opening angle of a propulsion device including an engine to generate a propulsive force to move the hull and an acceleration of the hull , or judging whether or not the hull is being loaded onto a trailer on a basis of a throttle opening angle of a propulsion device including an engine to generate a propulsive force to move the hull and a pitch angle of the hull , or judging whether or not the hull is being loaded onto a trailer on a basis of a number of engine revolutions of a propulsion device including an engine to generate a propulsive force to move the hull and a pitch angle of the hull ; and, upon judging that the hull is being loaded onto the trailer , controlling the actuators to position the posture control tabs at retracted positions. <EOS>