PURPOSE: To enhance creep rupture strength and heat shock resistance of the titled alloy obtained by preparing a specific composition containing C, Si, Mn, Cr, Ni, W, B and comprising the remainder of Fe.

CONSTITUTION: Said heat resistant cast alloy has a composition containing 0.35W 0.6% C, 0.5W2.0% Si, 0.3W0.9% Mn, 0.04% or less P, 0.04% or less S, 24W30% Cr, 30W40% Ni, 3W6% W, 0.005W0.05% B and comprising the remainder of Fe substantially. Then, as a member used in a high temp. range in the vicinity of about 1,100°C, it has extremely excellent creep rupture strength and heat shock resistance.