An optical image stabilizer, in which a magnet and a coil are arranges such that they oppose each other. The Hall sensor is arranged such that one face thereof is opposed to one face of the magnet. The Hall sensor can easily detect the location of a group of lenses by generating a corresponding signal in response to a variation in magnetic force following a variation in the gap between magnets depending on the direction in which a group of lenses is driven, and simultaneously, in response to a variation in magnetic force that occurs when the group of lenses is displaced in the direction that intersects the direction of the gap.