PURPOSE: To enable automatic crusing with a simple operation even for the use with changing the destination relatively by setting the direction with the operation of an operator and then doing steering control in accordance with the extracted azimuth shift and course shift.

CONSTITUTION: By operating an operator provided to an autopilot device 2 for setting a direction, a hypothetical course from the present self ship position to the set direction is set. Then, the course shift data of the self ship from the hypothetical course is extracted and the extracted course shift is output as a course shift data to the device 2. On the other hand, the set direction is read with a set direction reading means and the read set direction data is output to a crusing device 1. Next, the course shift data is input from the device 1 using the course shift data input means and the azimuth shift data of the self ship head from the set direction is extracted with an azimuth shift extraction means. Thus, steering control is done after correcting the direction using a steering device based on the azimuth and course shift data.