Abstract: An armature device of a printing head for use in a wire printer includes stylus having a free end to strike a recording medium, an armature connected to the stylus for reciprocating the stylus in a longitudinal direction thereof, a permanent magnet for generating a magnetic flux, a core for conducting the magnetic flux into the armature to form a magnetic path, a coil winding wound around the core for selectively substantially cancelling the magnetic flux, and a spring member having a free end supporting the armature for spring biasing the armature away from the core. The armature has a generally elongated shape, and a transverse groove formed in an end portion of the armature. The end portion of the armature has a first portion forming one wall of the groove and a second portion forming the other wall of the groove, the first and second portions opposing each other along the longitudinal direction of the armature. One of the walls is higher than the other wall.