An imaging device comprising: an imaging optical system including a wide-angle optical system and a telephoto optical system which are provided in different regions; a directional sensor that includes a plurality of pixels including photoelectric conversion elements which are two-dimensionally arranged, pupil-divides light beams which are incident through the wide-angle optical system and the telephoto optical system, and selectively receives the light beams; a pan/tilt mechanism that moves a direction of an imaging optical axis of the telephoto optical system with respect to a direction of an imaging optical axis of the wide-angle optical system; and an image acquisition unit that acquires a wide-angle image received from the directional sensor through the wide-angle optical system and a telephoto image received from the directional sensor through the telephoto optical system, wherein the wide-angle optical system of the imaging optical system is a circular central optical system and the telephoto optical system of the imaging optical system is an annular optical system that is provided concentrically with the central optical system and includes a reflection optical system that reflects the light beam two or more times, wherein the reflection optical system of the telephoto optical system includes at least a main reflection optical system that reflects the light beam and a sub-reflection optical system that further reflects the light beam reflected by the main reflection optical system, and the pan/tilt mechanism tilts the main reflection optical system with respect to a light receiving surface of the directional sensor in directions of rotation about two orthogonal axes and tilts the sub-reflection optical system by an angle that is half of a tilt angle of the tilted main reflection optical system. an imaging optical system including a wide-angle optical system and a telephoto optical system which are provided in different regions; a directional sensor that includes a plurality of pixels including photoelectric conversion elements which are two-dimensionally arranged, pupil-divides light beams which are incident through the wide-angle optical system and the telephoto optical system, and selectively receives the light beams; a pan/tilt mechanism that moves a direction of an imaging optical axis of the telephoto optical system with respect to a direction of an imaging optical axis of the wide-angle optical system; and an image acquisition unit that acquires a wide-angle image received from the directional sensor through the wide-angle optical system and a telephoto image received from the directional sensor through the telephoto optical system, wherein the wide-angle optical system of the imaging optical system is a circular central optical system and the telephoto optical system of the imaging optical system is an annular optical system that is provided concentrically with the central optical system and includes a reflection optical system that reflects the light beam two or more times, wherein the reflection optical system of the telephoto optical system includes at least a main reflection optical system that reflects the light beam and a sub-reflection optical system that further reflects the light beam reflected by the main reflection optical system, and the pan/tilt mechanism tilts the main reflection optical system with respect to a light receiving surface of the directional sensor in directions of rotation about two orthogonal axes and tilts the sub-reflection optical system by an angle that is half of a tilt angle of the tilted main reflection optical system.