An automatic steering device, comprising: a route calculating module configured to calculate a desired route to turn a ship based on positions of a plurality of waypoints (P, P1, P2) which are target points of a desired traveling route for the ship; a command steering angle calculating module configured to calculate a command steering angle; and a steering controlling module configured to control a steering mechanism of the ship based on the command steering angle, characterized in that: the device further comprises an intermediate waypoint calculating module configured to calculate an estimated intermediate waypoint, which is an estimated passing position ahead of the ship through which it is estimated that the ship will pass; the command steering angle calculating module is configured to calculate the command steering angle based on a positional relationship between: a) the desired route to turn the ship calculated by the route calculating module based on the positions of the plurality of waypoints (P, P1, P2) which are target points of a desired traveling route for the ship, and b) the estimated intermediate waypoint which is an estimated passing position ahead of the ship through which it is estimated that the ship will pass; the command steering angle calculating module is configured to calculate the command steering angle prior to arrival of the ship at the estimated intermediate waypoint; the intermediate waypoint calculating module is configured to calculate a distance (Ds) from a current position of the ship to the estimated intermediate waypoint based on a response of the ship to the command steering angle and a speed of the ship; and the intermediate waypoint calculating module is configured to calculate a direction from the current position of the ship to the estimated intermediate waypoint based on a set heading of the ship and a current heading of the ship. a route calculating module configured to calculate a desired route to turn a ship based on positions of a plurality of waypoints (P, P1, P2) which are target points of a desired traveling route for the ship; a command steering angle calculating module configured to calculate a command steering angle; and a steering controlling module configured to control a steering mechanism of the ship based on the command steering angle, characterized in that: the device further comprises an intermediate waypoint calculating module configured to calculate an estimated intermediate waypoint, which is an estimated passing position ahead of the ship through which it is estimated that the ship will pass; the command steering angle calculating module is configured to calculate the command steering angle based on a positional relationship between: a) the desired route to turn the ship calculated by the route calculating module based on the positions of the plurality of waypoints (P, P1, P2) which are target points of a desired traveling route for the ship, and b) the estimated intermediate waypoint which is an estimated passing position ahead of the ship through which it is estimated that the ship will pass; the command steering angle calculating module is configured to calculate the command steering angle prior to arrival of the ship at the estimated intermediate waypoint; the intermediate waypoint calculating module is configured to calculate a distance (Ds) from a current position of the ship to the estimated intermediate waypoint based on a response of the ship to the command steering angle and a speed of the ship; and the intermediate waypoint calculating module is configured to calculate a direction from the current position of the ship to the estimated intermediate waypoint based on a set heading of the ship and a current heading of the ship. the device further comprises an intermediate waypoint calculating module configured to calculate an estimated intermediate waypoint, which is an estimated passing position ahead of the ship through which it is estimated that the ship will pass; the command steering angle calculating module is configured to calculate the command steering angle based on a positional relationship between: a) the desired route to turn the ship calculated by the route calculating module based on the positions of the plurality of waypoints (P, P1, P2) which are target points of a desired traveling route for the ship, and b) the estimated intermediate waypoint which is an estimated passing position ahead of the ship through which it is estimated that the ship will pass; a) the desired route to turn the ship calculated by the route calculating module based on the positions of the plurality of waypoints (P, P1, P2) which are target points of a desired traveling route for the ship, and b) the estimated intermediate waypoint which is an estimated passing position ahead of the ship through which it is estimated that the ship will pass; the command steering angle calculating module is configured to calculate the command steering angle prior to arrival of the ship at the estimated intermediate waypoint; the intermediate waypoint calculating module is configured to calculate a distance (Ds) from a current position of the ship to the estimated intermediate waypoint based on a response of the ship to the command steering angle and a speed of the ship; and the intermediate waypoint calculating module is configured to calculate a direction from the current position of the ship to the estimated intermediate waypoint based on a set heading of the ship and a current heading of the ship.