A discharge lamp includes a coaxial waveguide for high-frequency electromagnetic wave transmission and a discharge tube for emitting light of discharge by plasma generated by electromagnetic waves. The coaxial waveguide includes an internal conductor and a pipe-shaped external conductor surrounding the internal conductor. The discharge tube is attached to a top of the coaxial waveguide, and is constructed in a double end shape in which both ends of a glass tube are pinched and sealed. The glass tube includes an ellipse spherical bulged part formed in a middle of a longitudinal direction. An inside of the ellipse spherical bulged part forms discharge space. A conductor assembly is sealed and attached to at least a proximal side pinch seal part. The proximal side pinch seal part of the discharge tube is inserted and held in a top opening of the coaxial waveguide.