Hajj Siran () is a village in Qareh Poshtelu-e Pain Rural District of Qareh Poshtelu District in Zanjan County, Zanjan province, Iran.
At the time of the 2006 National Census, the village's population was 383 in 83 households. The following census in 2011 counted 318 people in 87 households. The 2016 census measured the population of the village as 321 people in 106 households. It was the most populous village in its rural district.