To highly accurately and easily manufacture an armature of a high strength and a high magnetic permeability.

An armature 16 is formed of a lever element 18 which is formed by press working with the use of a melt-formed plate of maraging steel and a plunger 17 which is formed with the use of a kneaded formation material of Permendur powder and a binder and which is welded to the lever element 18 after the binder is removed and sintering is carried out. A nitrided layer is formed to a surface of the armature. A strength of the lever element 18 is enhanced and a magnetic permeability of the plunger 17 is increased. Since the plunger 17 having a small percentage of contraction after the binder is removed and the lever element 18 naturally not including the binder and having a considerably small percentage of contraction are welded, the two can be bound in a correct correspondence and moreover, a strength of a welded part of the two is enhanced by the nitrided layer.