A gas turbine includes a turbine blade including a leading edge, a trailing edge, and a plurality of partition walls defining a cooling passage for passing cooling air inside the turbine blade, a first partition wall of the plurality of partition walls facing the leading edge; and an injection nozzle disposed in the first partition wall to cool an inner surface of the leading edge. The injection nozzle includes a nozzle protrusion protruding from the first partition wall toward the leading edge and surrounding an injection hole formed in the first partition wall. Thus, a flow direction of cooling fluid to be supplied to the leading edge can be guided, and deformation and damage to turbine blade components can be prevented.