蒙特塞居（法语：Montségur）是法国阿列日省的一个市镇，属于富瓦区（Foix）拉韦拉内县（Lavelanet）。该市镇2009年时的人口为109人。

蒙特塞居人口变化图示

数据来源：INSEE

Montségur is a commune in the Ariège department in southwestern France.

It is famous for its fortification, the Château de Montségur, that was built on the "pog" (mountain) on the ruins of one of the last strongholds of the Cathars. The present fortress on the site, though described as one of the "Cathar castles," is actually of a later period. It has been listed as a historic site by the French Ministry of Culture since 1862.