A projection system includes a plurality of projection apparatuses. Each of the plurality of projection apparatuses includes a projection unit configured to project an image onto a projection surface, and an adjusting unit configured to adjust a state of displaying an image projected onto the projection surface by the projection unit. The projection system further includes a controller configured to cause the projection units of the plurality of projection apparatuses to simultaneously project a test image in different forms. The controller controls the adjusting unit of the plurality of projection apparatuses to adjust a state of displaying an image projected on the projection surface by the projection unit based on each state of displaying of the test images in different forms.