Qaleh Sar () is a village in Poshtkuh Rural District of Chahardangeh District in Sari County, Mazandaran province, Iran.
At the time of the 2006 National Census, the village's population was 413 in 105 households. The following census in 2011 counted 433 people in 125 households. The 2016 census measured the population of the village as 381 people in 135 households.