Experiments of piercing TiAl intermetallic compound using single mode pulse CO₂ laser were carried out. Influences were examined of kinds of assist gases and thicknesses of workpieces on piercing behavior. Radii and circularity of the holes were measured. The length of cracks propagating from the holes during piercing and hardness distributions near the holes were also evaluated. TiAl specimens of thickness of 4mm are able to be pierced by CO₂ laser. The maximum value of the ratio of the specimen thickness to the hole diameter achieved is about 10. With O₂ as assist gas, specimens can be pierced by lower beam power than that for piercing them with N₂ or Ar. Kinds of assist gases, average beam power and thicknesses of specimens influence the length of cracks propagating from the holes. TiAl near the holes is hardened by piercing apparently.