A linear actuator includes an inner yoke, an outer yoke and a coil for generating a magnetic field between the outer yoke and the inner yoke. The outer yoke includes a first facing portion facing the inner yoke and a second facing portion which faces the inner yoke. An insulating coil bobbin around which the coil is wound includes an engaging part which engages with both the first facing portion and the second facing portion of the outer yoke. A magnet is disposed between the inner yoke and the outer yoke and a movable body is integrally connected with the magnet. An alternating magnetic field is generated by the coil such that the movable body along with the magnet is reciprocally moved in the axial direction in conjunction with the alternating magnetic field.