A dual lens optical system (OS) includes a photographing device, a first OS having a first reflection member and redirecting an optical axis of light representing an image of an object input from a first direction toward the photographing device, and a second OS having a second reflection member, redirecting an optical axis of light representing an image of an object input from a second direction toward the photographing device, and sharing at least one of optical elements of the first OS. The first and second OSs selectively redirect the image light from the first or second direction toward the photographing device. The photographing surface has a first region where the light representing the image of the object input through the first OS is formed, and a second region where light representing the image of the object input through the second OS is formed, have different sizes and are overlapped.