A method of adjusting a posture of a 6-axis robot standing in a direction perpendicular or substantially perpendicular to a robot mounting surface includes specifying axis central positions of three axes located at different heights in the direction perpendicular or substantially perpendicular to the robot mounting surface of the 6-axis robot, specifying two planes including two arcs of which rotation centers are represented by two axes farther away from the robot mounting surface among the three axes, specifying a position of a predetermined point on the arc farther away from the robot mounting surface among the two arcs, and determining an angle adjustment amount of the three axes in a rotation direction and an angle adjustment amount of an axis extending between the two axes in a rotation direction based on the specified axis central positions of the three axes, the specified two planes, and the specified position of the predetermined point.