To provide a method for manufacturing a stock 1 for a transition piece used for a gas turbine with a small amount of material.

In the method for manufacturing the stock for the transition piece used for the gas turbine, a circular ring 2 is manufactured by performing the swaging, drilling, hole-expansion forging, and ring-rolling of a billet, a part for forming a corner of the circular ring 2 is partially heated, and the heated part is bent by using an inner forging die 32 corresponding to the inner shape of the corner and an outer forging die 42 corresponding to the outer shape of the corner. Then, the part is subjected to heat treatment such as solid solution heat treatment, and further machined.