AIR CIRCUIT BREAKER

The invention discloses an air circuit breaker, and the air circuit breaker comprises, among a plurality of magnetic iron plates of a fixed iron core, mounting sections provided on some of the magnetic iron plates. In this invention, a driving shaft is led out to the exterior of the fixed iron core through a gap provided in the magnetic iron plates having the mounting sections. The fixed iron coreis fixed via the mounting sections onto ribs provided on an insulation casing, thereby setting the position of the central axis of the driving shaft relative to the insulation casing. 固定铁芯具备在多个磁性铁板中的一部分磁性铁板设置的安装部，驱动轴经由在设置有安装部的磁性铁板所设置的间隙被导出至固定铁芯的外部，固定铁芯通过安装部固定于在绝缘框体设置的肋，由此，对驱动轴的中心轴相对于绝缘框体的位置进行设定。