A lens driving device, comprising: a cover member including an opening and a rotation prevention part; a housing; a bobbin disposed in the housing; a coil disposed on the bobbin; a first magnet disposed on the housing and facing the coil; a second magnet disposed on the bobbin; and a sensor disposed on the housing and facing the second magnet, the sensor comprises an upper surface, a lower surface disposed opposite the upper surface, an inner surface facing the second magnet, an outer surface disposed opposite the inner surface, and both lateral surfaces connecting the inner surface and the outer surface, the rotation prevention part is extended from an inner side of an upper plate of the cover member to a lower side, the rotation prevention part is configured to prevent the bobbin from rotating, the rotation prevention part is extended from an inner circumferential surface of the upper plate at the cover member to prevent the bobbin from rotating, a portion of the rotation prevention part is accommodated into a groove formed on an upper surface of bobbin, and the rotation prevention part is so formed as to be accommodated into the groove of bobbin as to allow at least of a lateral part of the rotation prevention part to be in contact with the bobbin when the bobbin is rotated, characterized in that the upper surface of the sensor is fixed to the housing, the cover member is formed of a magnetic material, such that the cover member functions as a yoke, a sensing magnet reception part is formed at one side of the bobbin, the sensing magnet reception part accommodates at least one portion of the sensing magnet, and the sensing magnet reception part is formed by being recessed into the bobbin. a cover member including an opening and a rotation prevention part; a housing; a bobbin disposed in the housing; a coil disposed on the bobbin; a first magnet disposed on the housing and facing the coil; a second magnet disposed on the bobbin; and a sensor disposed on the housing and facing the second magnet, the sensor comprises an upper surface, a lower surface disposed opposite the upper surface, an inner surface facing the second magnet, an outer surface disposed opposite the inner surface, and both lateral surfaces connecting the inner surface and the outer surface, the rotation prevention part is extended from an inner side of an upper plate of the cover member to a lower side, the rotation prevention part is configured to prevent the bobbin from rotating, the rotation prevention part is extended from an inner circumferential surface of the upper plate at the cover member to prevent the bobbin from rotating, a portion of the rotation prevention part is accommodated into a groove formed on an upper surface of bobbin, and the rotation prevention part is so formed as to be accommodated into the groove of bobbin as to allow at least of a lateral part of the rotation prevention part to be in contact with the bobbin when the bobbin is rotated, characterized in that the upper surface of the sensor is fixed to the housing, the cover member is formed of a magnetic material, such that the cover member functions as a yoke, a sensing magnet reception part is formed at one side of the bobbin, the sensing magnet reception part accommodates at least one portion of the sensing magnet, and the sensing magnet reception part is formed by being recessed into the bobbin.