A linear actuator includes a driving part having an inner yoke, an outer yoke and a coil for generating an alternating magnetic field and includes a movable body provided with a magnet disposed between the inner yoke and the outer yoke. The movable body is formed in a tubular shape having an aperture edge part at least one end is opened, and the aperture edge part or a portion near the aperture edge part disposed between the inner yoke and the outer yoke is positioned closer to the inner yoke side than to the outer yoke side. Alternatively, the linear actuator may includes an expansion preventing member which is disposed at the aperture edge part or the portion near the aperture edge part for preventing the aperture edge part from expanding.