Abstract: An image projection apparatus to which a projection lens unit configured to project image light onto a projection surface is detachably attached includes a controller configured to control the shifter so as to shift one unit of the projection lens unit and the light modulation unit within a shift permissible range relative to the other unit. When the projection lens unit is attached to the image projection apparatus and the one unit is located outside the shift permissible range relative to the other unit, the controller controls the shifter so as to shift, within the shift permissible range, the one unit to a second position that can be reached by a shift amount shorter than a shift amount to a first position that is a reference position for the other unit, and to stop the one unit there.