Miyan Kaleh Rural District () is in the Central District of Behshahr County, Mazandaran province, Iran. Its capital is the village of Zagh Marz.
At the time of the 2006 National Census, the rural district's population was 18,320 in 4,737 households. There were 17,355 inhabitants in 5,197 households at the following census of 2011. The 2016 census measured the population of the rural district as 18,469 in 6,026 households. The most populous of its 69 villages was Zagh Marz, with 5,932 people.