An iridium-based alloy which has L12-type intermetallic compounds dispersedly precipitated therein and has a basic composition including, in terms of mass proportion, 0.1 to 9.0% Al, 1.0 to 45% W, and Ir as the remainder. The component system containing 0.1 to 1.5% Al has L12-type intermetallic compounds dispersedly precipitated therein. The component system containing 1.5 to 9.0%, excluding 1.5%, Al has L12-type and B2-type intermetallic compounds dispersedly precipitated therein. Part of the Ir may be replaced with an element (X) (Co, Ni, Fe, Cr, Rh, Re, Pd, Pt, or Ru) and part of the Al and W may be replaced with an element (Z) (Ni, Ti, Nb, Zr, V, Ta, Hf, or Mo). The iridium-based alloy, which contains L12-type intermetallic compounds [1r3(Al,W) and [(Ir, X)3(Al, W, Z)] dispersedly precipitated therein, has a high melting point. The lattice constant mismatch between the L12-type intermetallic compounds, i.e., [Ir3 (Al, W)] and [(Ir, X)3(Al, W, Z)], and the matrix is small and, hence, the iridium-based alloy is excellent in high-temperature strength and structural stability.