Kushkak () is a village in, and the capital of, Kushkak Rural District of Qohestan District, Darmian County, South Khorasan province, Iran.
At the time of the 2006 National Census, the village's population was 867 in 251 households, when it was in Qohestan Rural District. The following census in 2011 counted 858 people in 256 households. The 2016 census measured the population of the village as 877 people in 277 households.
After the 2016 census, Kushkak was transferred to Kushkak Rural District created in Qohestan District.