A linear actuator is provided with an outer tube and an inner tube inserted in the outer tube so as to be free to slide axially. A rod is erected at a central axis part of the inner tube, forming an annular space between the rod and the inner tube. Permanent magnets are retained along an axial direction in the rod, and a holder is fixed to the outer tube for retaining coils which are disposed face to face with the permanent magnets. The holder includes a cylindrical coil holding portion inserted in the annular space such that an extreme end of the cylindrical coil holding portion can move further into and backward from the annular space. The coil holding portion retains the coils within an inner peripheral surface, and a flange portion joined directly to a proximal end of the coil holding portion is fixed to the outer tube.