PURPOSE: To produce a cast material for tool excellent in wear resistance, seizure resistance, and crack resistance by subjecting a cast high alloy steel having a specific composition consisting of C, Si, Mn, Cr, Ni, S, P, O, and Fe to specific heat treatment.

CONSTITUTION: A cast high alloy steel which has a composition consisting of, by weight, 0.7-2.5% C, ≤3% Si, ≤3% Mn, 20-40% Cr, 20-50% Ni, ≤0.05% S, ≤0.05% P, ≤0.10% O, and the balance Fe with inevitable impurities and further containing, if necessary, either or both of 0.0001-0.050% Ca and 0.0001-0.50% REM and/or one or more kinds among 0.1-5.0% Mo, 0.1-5;0% W, 0.1-5.0% CO, 0.1-5.0% Ti, 0.1-5.0% V, and 0.1-5.0% Zr is heated and held at a temp. in the region between (solidus temp. -20°C) and (solidus temp. +40°C) for 1-20hr. By this method, a high temp. tool material free from the occurrence of cracks in many localities even if subjected to severe heating-cooling cycle or bearing and having long service life can be obtained.