PURPOSE: To enable easy steering control with high precision by finding and displaying thrust to act on an actuator and the whole ship through a process of vector-adding the thrust data in a steering controlling and supporting device for controlling steering while distributing calculated operating thrust to respective actuators through a distributing means.

CONSTITUTION: The operating thrust is calculated by a calculating means 13 on the basis of the output of a joy stick lever 11 as a steering means and a turning dial 12, and the operating thrust is distributed to respective actuators as a thruster 92S, a main propulsion machine 92P and a rudder 92R by a thrust distributing means 4. In a displaying and calculating means 6, thrust to act on the actuators or the whole ship is found by vector-adding one data selected from the operating thrust from an operating thrust calculating means 13, a command value from the thrust distributing means 4, or the thrust data taken from thrust control means 91S, 91P, 92R or detecting means 84 to 86, and the obtained thrust is vector-displayed on a display 7.