Sain Qaleh Rural District () is in the Central District of Abhar County, Zanjan province, Iran. Its capital is the village of Amidabad.
At the time of the 2006 National Census, the rural district's population was 12,005 in 2,901 households. There were 11,645 inhabitants in 3,440 households at the following census of 2011. The 2016 census measured the population of the rural district as 10,833 in 3,372 households. The most populous of its 17 villages was Amidabad, with 2,147 people.