To enable the thrust of a linear actuator comprised of a driving magnet and a drive coil to act in a fixed and stable manner, the present invention is a lens driving device that comprises a driven body supporting an optical lens capable of freely moving along an optical axis direction, a drive coil fitted to the driven body, and a magnet having a surface set so as to have a prescribed gap with the moving drive coil, wherein a gap between the surface of the magnet and the drive coil is set in such a manner as to be broader at a central part of the range of movement of the drive coil than at an end part.