PURPOSE: To prevent the crumbling of the balance of the internal stress of a member thereby improving the operation accuracy of a linear pulse motor by performing both-side etching for a secondary iron core, and forming irregularity equivalent to a magnetic tooth at the rear of a magnetic pole tooth face.

CONSTITUTION: In the figure, Λa is a magnetic pole tooth formed by etching, and Λb is a groove removed by etching. And a stator not shown in the figure is provided opposite to the magnetic tooth 1a and the groove 1b. In this example, also at the rear of this magnetic pole tooth, a projection 1c and a recess 1d, which are formed in the patterns equivalent to the magnetic pole tooth Λa and the groove 1b, are provided by etching. Performing the processing equivalent to the magnetic pole tooth also to the rear of the magnetic pole tooth face, the balance of the internal stress inside the secondary iron core shown by an arrow in the figure does not crumble, and as a result, the plane accuracy before the etching can be maintained. Therefore, the magnetic pole teeth are formed at correct pitches, and the operation accuracy of a linear pulse motor can be improved.