The light of a broad energy band can be observed by reflecting the light of the broad energy band, for example, the light from the visible light region to the x-ray region at a high reflectance respectively, by a composite telescope including a normal incidence optical system and an oblique incidence optical system. A broadband telescope comprise an oblique incidence optical system unit in which the light is obliquely incident on a surface part for reflecting the incident light, a normal incidence optical system unit in which the light is substantially vertically incident on a surface part for reflecting the incident light, and an analyzer for spectrum analysis of the light reflected by the surface part of the obliquely incidence optical system unit and the light reflected by the surface part of the normal incidence optical system unit.