A projection system includes a projection device that projects drawings individually onto a plurality of work spots in a work site. The projection device includes a driver that changes an orientation of the projection device. When drawings are individually projected onto a first work spot and a second work spot in a stated sequence, and the second work spot is outside a projection angle that is projectable by the projection device, the driver changes the orientation of the projection device to include the second work spot within the projection angle after work at the first work spot is finished. The first work spot and the second work spot are included in the plurality of work spots.