Hasan Su () is a village in Howmeh Rural District of the Central District in Samalqan County, North Khorasan province, Iran.
At the time of the 2006 National Census, the village's population was 728 in 178 households. The following census in 2011 counted 736 people in 208 households. The 2016 census measured the population of the village as 622 people in 198 households.