A discharge lamp includes: an emitting portion in which a pair of electrodes are disposed, an electric discharge being generated between the pair of electrodes so as to emit light; at least either one electrode of the pair of the electrodes including: a small-diameter portion; and a large-diameter portion provided on an end of the small-diameter portion closer to the other electrode, the large-diameter portion having a larger diameter than the small-diameter portion; and the large-diameter portion including a projecting part, the projecting part projecting outward from the large-diameter portion.