In order to realize a stabilized pivotal movement of an armature to thereby obtain pivotal force required for high-speed printing, a pivot shaft is held such that an armature having an attracted face that is in contact with a core, that has a coil wound therearound and has a pole face, and the pivot shaft is opposed to the core, whereby the armature becomes pivotable. An attracting direction of attraction force F acted on the attracted face by the core and the moving direction in which the attracted face moves due to the attraction force F are made substantially equal to each other.