A system displays an image using a plurality of projection type display devices, and is capable of reliably notifying a user who uses the system that an error has occurred in a certain projection type display device. A slave includes a display unit that projects and displays an image and a signal receiving unit that receives data transmitted from a commander. The slave includes a detection unit that detects an error in the commander on the basis of the receiving conditions of the data in the signal receiving unit. The slave includes a display control unit that, when an error is detected by the detection unit, makes the display unit display an image showing that the error has been detected.