This method for manufacturing a high-temperature component formed of a Ni-based alloy includes a step of subjecting a workpiece of the Ni-based alloy to hot die forging using predetermined dies to form a forge-molded article, the step including: a die/workpiece co-heating substep of heating the workpiece interposed between the dies to a forging temperature; and a hot forging substep of taking out the workpiece and the dies into a room temperature environment and immediately performing hot forging on the workpiece using a press machine. The predetermined dies are formed of another Ni-based superalloy comprising γ and γ′ phases, and have features in that: a solvus temperature of the γ′ phase is 1050-1250° C.; and the γ′ phase precipitates at least 10 vol. % at 1050° C. and has two kinds of forms of intra-grain γ′ phase precipitations within the γ phase grains and inter-grain γ′ phase precipitations between/among the γ phase grains.