PURPOSE: To enable emergency stopping and emergency sternway to be steered by cancelling a steering mode having been followed with an emergency steering means actuated, steering both of high lift rudders to an angle at which the maximum astern force can be obtained, and thereby letting propeller slip stream be directed to the direction of sternway by means of the high lift rudders.

CONSTITUTION: When an emergency astern push-button means 34 is actuated at the time of emergency, an emergency steering means 32 allows a rudder control means 38 to output a maximum rudder angle signal to both of rudders at the port and the starboard. Meanwhile, a steering engine emergency mode switch-over means 39 issues a start command signal to the right and left original and auxiliary hydraulic pumps of the rudder control means 38 upon receiving an actuation signal from the emergency astern push-button means 34. By this constitution, the rudder control means 38 actuates a steering engine so as to control it in such a way as to correspond to the right and left maximum rudder angle signals. By this constitution, a normal steering mode is cancelled, and the rudder angles of both the high lift rudders are steered in such a way that the maximum astern force can be obtained, so that propeller slip streams are thereby directed to the direction of sternway.