To safely project a desired projection image in any projection area, provided is a projection system including: a projection device projecting light forming display information in a projection area; an imaging device capturing a range including the projection area; and a control device controlling to cause the projection device to project light and the imaging device to capture the projection area. The control device includes: an analysis circuit accumulating image information about the projection area captured by the imaging device and detects an abnormality in the projection area by comparing any one piece of accumulated image information about the projection area with image information about the projection area most recently captured by the imaging device; and a safety control circuit executing safety control to change a projection condition for the projection device when an abnormality is detected in the projection area by the analysis circuit.