A projection type image display device correctly detects the position of contact of an electronic pen and a finger on a manipulation surface without the provision of a touch sensor. Light containing an image is projected, illuminating light that is different from the light containing the image is projected onto a manipulation surface which at least partially overlaps an image projection surface onto which the light has been projected, and an image of the manipulation surface is captured. A first detection process detects the position at which a first object being manipulated, a distal end of which emits light, touches the manipulation surface, a second detection process detects the position at which a second object being manipulated, which does not emit light, touches the manipulation surface, and at least part of the image being displayed is changed on the basis of the detection result from either detection process.