There is provided a projection system including a plurality of projectors that perform edge blending, each of the plurality of projectors including: an image display element; a light blocking plate that reduces an amount of light in an edge overlapping portion of a light bundle; and an aperture diaphragm that changes an amount of light traveling-toward an object to be projected, wherein when a circle formed by an outermost perimeter of a light passing region obtained when the aperture diaphragm is completely opened is defined as a reference circle, the aperture diaphragm partially covers the inside of the reference circle such that an outline of the reference circle is divided into three or more sections in a state where the aperture diaphragm is narrowed to make an area of the light passing region inside the reference circle half the reference circle.