Au Sable is an unincorporated community and census-designated place in Iosco County, Michigan. The community is a part of Au Sable Charter Township, in the northeastern portion of the township. The community is located at the mouth of the Au Sable River, along the coast of Lake Huron. The community, on the south bank of the river, lies opposite the census-designated place of Oscoda. The population was 1,533 during the 2000 census.