To inexpensively and stably provide a cast impeller for a compressor composed of a titanium alloy having superior heat resistance and strength, and promising high aerodynamic performance.

This cast impeller for the compressor is formed by casting the titanium alloy in an impeller shape having a hub shaft, a hub disc part extending in the radial direction from the hub shaft, and a blade part arranged around the hub shaft. The titanium alloy contains in mass% 5.50-6.75% Al, 3.50-4.50% V, 0.01-3.0% B, 0.40 or less Fe, 0.40 or less C, 0.05 or less N, 0.015% or less H, and 0.25% or less O, with the balance being Ti and unavoidable impurities. The hub disc part is formed having an outer diameter of 30-250 mm.