Abstract: A projection display device includes an opening formed in a main body cabinet; a part to be attached in the main body cabinet through the opening; a cover which covers the opening; a detector which detects closure of the cover; and a first contact part and a second contact part which contact each other when the cover is being closed, thereby to prevent the cover from being closed up to a position where the closure is detected by the detector. When the part to be attached is not attached, the first contact part is positioned on a line contacting the second contact part at closure of the cover and is capable of evacuating to a position out of the line. The projection display device further includes an evacuation part to evacuate the first contact part to the position out of the line when the part to be attached is attached.