A control method of a projection system, that includes a first projection portion, a second projection portion and a processor, and performs projection based on a content image, includes: by the processor, setting, based on input information, a coordinate space corresponding to a non-projection range between a first projection range of the first projection portion and a second projection range of the second projection portion; and performing a control of generating a first projection image and a second projection image based on the set coordinate space and the content image, causing the first projection portion to project the first projection image, and causing the second projection portion to project the second projection image.