Isotherms of the Ir-rich portion of the Ir–Al–X (X: V, Nb, Ta) systems composed of fcc-Ir solid solution ((Ir) ss ), Ir-based L1 2 intermetallic compounds Ir 3 X and B2–IrAl are presented as a second report of a series of investigations on the phase equilibria in the (Ir or Rh)–Al–X (X: Ti, Zr and Hf, or, V, Nb and Ta) ternary systems. In both Ir–Al–Nb and Ir–Al–Ta systems fcc/L1 2 /B2 three-phase equilibrium is found. In Ir–Al–V system, Ir solid solution and Ir 3 V have close compositions each other and fcc/L1 2 /B2 three-phase equilibrium is expected. No ternary compound is observed in all of the isotherms. Solid solubility of each phase is confirmed by chemical analysis by wavelength dispersive X-ray spectroscopy (WDS). The direction of the solubility lobe of L1 2 –Ir 3 X with Al addition is explained in terms of the nearest neighbor interactions. Liquidus surfaces are also established by taking into account the microstructure of as-cast alloys, differential thermal analysis (DTA) data, and the Ir–Al and the Ir–X binary phase diagrams reported previously.