A linear actuator includes: a first tube provided with coils placed there inside, the coils being held by a yoke; a second tube mounted on an outer circumference of the first tube; a rod fixed to an end of the second tube at one end; permanent magnets held by the rod while being lined up in an axial direction; and a joint portion disposed at the outer side of the second tube, to be joined with an external device. The rod has a non-magnetic portion at the one end fixed to the second tube. The second tube includes: an outer tube formed along the outer circumference of the first tube; and a small diameter portion that is formed along an outer circumference of the non-magnetic portion of the rod and smaller in diameter than the outer tube. The joint portion is disposed at the outer side of an end face of the small diameter portion of the second tube.