Qahan District () is in Jafarabad County, Qom province, Iran. Its capital is the city of Qahan, whose population at the time of the 2016 National Census was 784 in 286 households.
After the 2016 census, Jafarabad District and Qahan Rural District were separated from Qom County in the establishment of Jafarabad County, which was divided into two districts of two rural districts each, with Jafariyeh as its capital and only city at the time. In 2018, the village of Qahan was elevated to the status of a city.