An electronic device includes an optical system. The optical system includes six lens elements, and the six lens elements are, in order from an outer side to an inner side: a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. Each of the six lens elements has an outer-side surface facing toward the outer side and an inner-side surface facing toward the inner side. Each of at least three lens surfaces of the six lens elements is aspheric and has at least one inflection point.