Disclosed are a heat-resistant alloy used in a heat-resistant bolt and the like for fastening high temperature parts of an engine in a vehicle and the like, and a method of manufacturing a heat-resistant bolt using the heat-resistant alloy. Particularly, the austenitic heat-resistant alloy includes, based on a total weight of the heat-resistant alloy, carbon (C) in an amount of about 0.01 to about 0.08 wt %, silicon (Si) in an amount of about 0.01 to about 1.00 wt %, manganese (Mn) in an amount of about 0.01 to about 2.00 wt %, nickel (Ni) in an amount of about 17 to about 22 wt %, titanium (Ti) in an amount of about 2.7 to about 3.2 wt %, chromium (Cr) in an amount of about 11 to 16 wt %, molybdenum (Mo) in an amount of about 0.3 to about 1.0 wt %, vanadium (V) in an amount of about 0.1 to about 0.4 wt %, and a remainder of iron (Fe) and optionally an inevitable impurity.