It is possible to reliably prevent dust particles from becoming attached to optical components and it is also possible to suppress temperature rises in optical components. A projection type display device according to the present invention includes a plurality of optical components (20, 21, 24, 30, and so on), a hollow structure (45, 50, or the like), and an air blow source (19, 46, or the like). The plurality of optical components are provided along the optical axis direction of light emitted from a light source. The hollow structure includes optical components (20, 24) that are to be protected from the attachment of dust particles to optical components among the plurality of optical components, and forms an enclosed space separated from the surroundings. Then, the source that blows air is provided in the inside of the enclosed space to circulate the internal air for cooling targets.