A projection apparatus includes a projection optical system, an output display element, an operation unit acquiring an adjustment instruction, a geometric correction adjustment unit, and a geometric correction unit. The output display element having an element region including pixels that modulate projection light by a quadrangular effective element region in the element region. The geometric correction adjustment unit transforms the effective element region to shift a vertex of the effective element region along a side, according to the adjustment instruction. The geometric correction unit performs an operation of projecting an input image on the effective element region.