Shirin Su Rural District () is in Shirin Su District of Maneh County, North Khorasan province, Iran. Its capital is the village of Kalimani. The previous capital of the rural district was the village of Khartut.
At the time of the 2006 National Census, the rural district's population (as a part of Maneh District in Maneh and Samalqan County) was 7,761 in 1,635 households. There were 8,819 inhabitants in 2,021 households at the following census of 2011. The 2016 census measured the population of the rural district as 9,618 in 2,241 households. The most populous of its 29 villages was Kohneh Jolgeh (now in Kohneh Jolgeh Rural District), with 2,010 people.
In 2023, the district was separated from the county in the establishment of Maneh County and renamed the Central District. The rural district was transferred to the new Shirin Su District.