In an optical device including an optical system to form an optical image of an object to be photographed, an image capture unit to convert the optical image of the object to be photographed into an electrical signal, and an optical device arranged on the front surface of the image capture unit, a water repellent layer or a structure with a three-dimensional pattern to reduce the adhesive force of an alien substance is provided on a surface of the optical element on the opposite side of the optical system.