Provided is a linear actuator whose entire length can be shortened while thrust thereof can be made large. The linear actuator of the present invention is provided with the following: a hollow drive magnet (11); a coil (4) disposed at either the outside or the inside of the drive magnet (11); and a return magnet (8) that is disposed at the other of the outside or the inside of the drive magnet (11), is connected to the coil (4), and returns the drive magnet (11) to the starting point. By conducting electricity to the coil (4), the drive magnet (11) or the coil (4) and the return magnet (8) move in the axial direction of the drive magnet 11.