PURPOSE: To reduce a partially generating crack by using the material for forming tool of an alloy which is a Ni base alloy of the γ' reinforcing element containing deposition reinforcing type and being made more than a specific hardness after the heat treatment.

CONSTITUTION: An alloy which is a Ni base alloy of the deposition reinforcing type and whose hardness after the heat treatment is made more than HRC 33, or which is a Co base alloy of 15 to 35wt.% Cr content and whose hardness after the heat treatment is made more than HRC 33 is used as the tool material for the hot elastic processing of the zinc content aluminum alloy. Because the tool is produced of the Ni base alloy or the Co base alloy, the zinc can be prevented from intruding into the tool material. Further, because it is a stable austenitic structure, the zinc can be prevented from intruding in the crystal grain range of the tool material. If the hardness is less than HRC 33, the wear resistance is not enough.