Disclosed herein are a method of manufacturing a Ni-based superalloy component for a gas turbine using a one-step process of hot isostatic pressing (HIP) and heat treatment, and a component manufactured by the method. In the method, an HIP process and a heat treatment process, which have been performed to manufacture or repair a Ni-based superalloy component for a gas turbine, are performed as a one-step process using an HIP apparatus. Thus, component defects, such as micropores and microcracks, which are generated when casting, welding, or brazing the Ni-based superalloy component for a gas turbine used for a combined cycle thermal power plant or airplane, can be cured using an HIP apparatus at high temperature and high pressure and, at the same time, the physical properties of the Ni-based superalloy component can be optimized using the heat treatment process.