An optical system is provided and includes a fixed module, a movable module, a driving assembly and a plurality of sliding members. The fixed module includes a base. The movable module includes an optical member holder and a driving frame unit. The optical member holder is configured to hold an optical member, and the driving frame unit is connected to the optical member holder. The driving assembly includes at least one first magnetic element and at least one second magnetic element. The second magnetic element corresponds to the first magnetic element and is configured to drive the driving frame unit with the optical member holder to move relative to the base. The sliding members are securely disposed on the fixed module or the movable module, so that the movable module is able to slide relative to the fixed module.