To improve reliability by making the holding strength of a magnetic circuit portion ample.

In a sub-panel 3 serving as the enclosure of a magnetically driven actuator, an external cylinder 3a is connected to an internal cylinder 3b in the top end by a plane. At least one part of this plane bulges inwardly, from the internal cylinder 3b to form a bulging portion 3c, and its end surface forms a top opening. A project 3f of a snap-fit portion is formed in the inside surface of the internal cylinder 3b, and a side surface through hole 7a, escaping from the project 3f, is provided to the external side surface of a damper 7. A notch 10a is formed on a position, corresponding to the project 3f of the side surface of a top plate 10. After assembling a coil 5, the project 3f is put to the side surface through hole 7a of the damper 7, and a ring 16 is fitted in the inside and is forcibly pressed. Thus, the damper 7 is fixed to the bottom surface of the top bulging portion 3c of the sub-panel 3 by means of a snap-fit method.