Patent ID: 8531093

Claim:
A discharge lamp, comprising: a glass member that comprises a light emitting part and that is formed so that it extends in a first direction; and a first base member having one end part that is coupled to an end part of the glass member on the first direction side; wherein the first base member comprises: a projecting part which is provided to one end part side of the first base member that protrudes in an orthogonal direction, which is orthogonal to the first direction; a first shaft part, which is provided between the projecting part and another end part of the first base member, the external shape of which is smaller than that of the projecting part in the orthogonal direction; a second shaft part, which is provided between the first shaft part and the other end part of the first base member, the external shape of which is smaller than that of the first shaft part in the orthogonal direction; a third shaft part, which is provided to the other end part side of the first base member, the external shape of which is smaller than that of the projecting part and larger than that of the second shaft part in the orthogonal direction; and a recessed part that is provided to at least part of an outer circumferential surface of the first shaft part and that is formed by a groove part that extends from the one end part side to the other end part side of the first base member, the recessed part fluidly or thermally communicates with one end part side of the first shaft part and a space between the first shaft part and the third shaft part.