To solve the problem that the degree of freedom for wavelength selection of detectable light is low.

In this film-shaped photosensor, a transparent optically- transmissible material, an upper layer electrode, a photosensitive dielectric layer containing a photosensitive dielectric material, a lower dielectric layer and a lower layer electrode are laminated, and a capacitor is constituted between both electrodes, and when the permittivity of the photosensitive dielectric layer is changed by admission of light, the capacity of the capacitor is changed, to thereby enable to detect the light intensity from the change. Zinc sulfide is used as the photosensitive dielectric material for exclusive use for an ultraviolet ray. The dielectric layer is provided between the photosensitive dielectric layer and the lower layer electrode for adjusting the capacity. A protective material is laminated on the back of the electrode. In this photosensor circuit, the film-shaped photosensor is used as a capacitor for a CR oscillator and an LC oscillator, and transmission frequencies of the oscillators are counted to thereby detect a capacity change of the capacitor of the film-shaped photosensor, and the light intensity can be detected from the change.