PURPOSE: To decide a focusing in any case of a visible light and an infrared ray by providing two view apertures of a visible light view apertures and an infrared light view aperture, and forming an image again by a common secondary image forming optical system.

CONSTITUTION: The first and the second view apertures 2a, 2b are provided in the vicinity of an expected image forming surface of a photographic lens 1, the first optical filter 3a having the first spectral transmittivity characteristic is provided in the vicinity of the first view aperture 2a, and the second optical filter 3b having a spectral transmittivity charcteristic being different from the first spectral transmittivity characteristic is provided in the vicinity of the second view aperture 2b. Subsequently, a pupil dividing means 6 and a secondary image forming lens 7 are placed in the rear of the expected image forming surface, images formed by the photographic lens 1, which are formed in the vicinity of the first and the second view apertures 2a, 2b are formed again, and on a position for photodetecting these images, each one pair of the first and the second photoelectric converting element trains 8a, 8c and 8b, 8d corresponding to images formed in the vicinity of the first and the second view aperture 2a, 2b are provided.