An optical system is provided, including a holder, a fixed module, a driving assembly, and a first resilient member. The holder is used for holding an optical element that defines an optical axis. The fixed module is movably connected to the holder and has a housing and a base connected to the housing. The base has a bottom surface parallel to the optical axis and a first pillar forming a first surface not parallel to the optical axis. The driving assembly drives the holder to move relative to the fixed module. The first resilient member is disposed on the first surface and movably connecting the holder with the fixed module.