PURPOSE: To enable a device to estimate behavior of a hull after a fixed time particularly from operating a joy stick lever, relating to the joy stick ship steering device.

CONSTITUTION: Based on an indication signal from a joy stick lever 10 and from a turn knob 11 and based on an output signal from a gyrocompass 8 and from a wind direction/speed meter 12, from a joy stick ship steering arithmetic part 9, a control signal, fed to each actuator 5 to 7 of a rudder angle adjusting system, propeller adjusting system and a bow thruster adjusting system, is input to also an input part 4, so that also each output signal from the gyrocompass 8, wind direction/speed meter 12 and a ship speedometer 13 is input to the input part 4. Accordingly, based on each signal input to this input part 4 and based on each data of a memory part 3 of storing data related to the dimension of a hull and resistance force and data related to the actuators 5 to 7, an arithmetic operation, estimating a hull position and bow bearing, is performed in a hull motion estimating arithmetic part 2, to display this result in a display part 1.