To provide a projection type display device capable of preventing the color purity of a display image from falling without bringing about a decrease in light use efficiency nor an increase in cost.

This projection type display device is provided with a light source for emitting white light, a first fly-eye lens for converting the white light into telecentric light whose principal ray is parallel to an optical axis, a second fly-eye lens for making the telecentric light transmit, a color separation optical element on which the telecentric light transmitting the second fly-eye lens is made incident and which performs color separation of the telecentric light made incident into three types of light having different colors from one another, three image display elements for respectively displaying three types of images corresponding to the respective three types of light, and a compositing means for compositing the three types of images and outputting the composite image to a projection lens to magnifyingly project the composite image to a screen.