The invention relates to a compact, slimmed-down, low-cost optical system and electronic equipment that incorporates the same. The optical system at least comprises a stop 2, at least one object-side reflecting surface 12 located on the object side with respect to the stop 2 and inclined from the optical axis of the optical system, at least one image-side reflecting surface 22, 23 located on the image side of the optical system with respect to the stop 2 and inclined from the optical axis, and an image pickup device 3. Regarding all reflecting surfaces inclined from the optical axis in the optical system, the reference plane for each reflecting surface is given by a plane defined by an entrance-side axial chief ray and a reflection-side axial chief ray regarding each reflecting surface. In the invention, the reference plane for at least one object-side reflecting surface 12 and the reference plane for at least one image-side reflecting surface 22, 23 cross at any angle, and at least one object-side reflecting surface 12 and at least one image-side reflecting surface 22, 23 have a rotationally asymmetric aspheric shape.