An arc tube provided with a central sealed chamber 12, in which light-emitting substances are enclosed, having a pair of electrode assemblies disposed opposite to each other. The electrode assemblies are sealed in pinch seal portions 13. The arc tube incorporates a residual-compressive-stress layer 16 formed on a surface of the glass layer 15 in each of the pinch seal portions 13 that contacts the electrode rod 6 included in each electrode assembly. The residual-compressive-stress layer has a length greater than or equal to 30% of the axial length of a glass layer region that only contacts the electrode rod 6 and/or an angular range greater than or equal to 180° in a circumferential direction of the electrode rod. Thermal stress (tensile stress) produced in the boundary between the glass layer 15 and the electrode rods 6 after the arc tube 10 has been turned on is absorbed and dispersed by the residual-compressive-stress layer 16 surrounding the electrode rods 6. Thus, any vertical crack that would result in the light-emitting substances leaking from the sealed chamber does not form in the glass layer 15 of the pinch seal portions 13.