The Hay Gaol is a heritage-listed former prison and now museum at 355 Church Street, Hay, Hay Shire, New South Wales, Australia. It was an adult prison from 1880 to 1915 and 1930 until 1940, a prisoner-of-war camp during World War II, and a juvenile facility, the Hay Institution for Girls, from 1961 to 1974. It was designed by James Barnet and Colonial Architect and built from 1879 to 1880 by Witcombe Brothers. The site faces Church Street, and is otherwise bounded by Piper, Macauley and Coke Streets, north-east of the town centre. It was added to the New South Wales State Heritage Register on 13 March 2009.