The present invention is directed to the provision of a reflecting mirror that suppresses decreases in the resolution performance and contrast performance by decreasing the mean surface roughness. In a projection type image display apparatus including a projector lens that expansion projects the image light from an image generating source and a reflecting mirror that guides the image light from the projector lens to the back face of the screen, according to the present invention, a silver reflecting surface (2) is formed on the substrate (1) of the reflecting mirror, a protective layer (3) of a transparent resin is formed thereon, and the mean surface roughness of the silver reflecting layer is made to be 1.8 nm or less.