The projection image adjustment system includes: projection display apparatuses for projecting projection images; a first and a second imaging apparatus for shooting the projection images; and a controller. The controller includes: an imaging-apparatus selecting unit, a shooting-region setting unit, a pattern projection unit, and a shot-image display unit. The imaging-apparatus selecting unit selects the first or the second imaging apparatus. The shooting-region setting unit sets a first and a second charge-of-shoot region for a projection display apparatus. The first and the second imaging apparatus are respectively in charge of shooting the first and the second charge-of-shoot region. At least one projection display apparatus is shared by the first and second charge-of-shoot regions. The pattern projection unit projects a format pattern of the projection display apparatus corresponding to the first or the second charge-of-shoot region. The shot-image display unit displays an image of the first or the second imaging apparatus.