A projector controlling method including projecting, by a projector, a projection image by using first setting values with the projector attached to a base apparatus that specifies the direction in which the projector projects projection light and the position where the projector is installed, changing the settings of the projector from the first setting values to second setting values when the projector is detached from the base apparatus, and changing the settings of the projector from the second setting values to the first setting values when the projector detects that the projector is attached to the base apparatus, and the set of first setting values and the set of second setting values each including a parameter relating to geometric correction of the projection image.