an optical device and mobile device including a plurality of optical devices having different fields of view to increase an aberration improvement effect and to realize a higher degree of resolution are disclosed . the optical device includes first to sixth lenses disposed sequentially from an object , and an image sensor configured to convert an image of a subject incident through the first to sixth lenses into an electrical signal , wherein 0 . 7 & lt ; ttl / f & lt ; 1 . 0 . the mobile device includes a plurality of optical systems having different fields of view , wherein a difference between fields of the two optical devices of the plurality of optical devices is 20 degrees or more , and one optical device of the plurality of optical devices comprise , whereby a wide angle function and a telephoto function may be realized .