Production method and production system for magnetoresistance element

Provided are a production method and a production system for a magnetoresistance element that achieve a further decrease in the size of a magnetoresistance element and a further increase in degree of integration, and that make it possible to produce a magnetoresistance element having high magnetic properties. The production method for a magnetoresistance element comprises: a step in which a layered body is prepared on a substrate, said layered body being provided with one layer of two magnetic layers, a layer that constitutes a tunnel barrier layer, and the other layer of the two magnetic layers; a step in which the layered body is separated into a plurality of layered bodies by etching and a plurality of layered bodies are thereby formed on the substrate; a step in which side sections of the plurality of separated layered bodies are irradiated with an ion beam within a treatment chamber that can be depressurized; and a step in which an oxidizing gas or a nitriding gas is introduced into the treatment chamber