A metal vapor discharge lamp and a lighting fixture are downsized without causing breakage of an outer tube because of optimization of a positional relation among the outer tube (34), an inner tube (32), and an arc tube (40). The metal vapor discharge lamp has the arc tube, the inner tube housing the arc tube, and the outer tube housing the inner tube. The positional relation satisfies the relation of 2.times.A+B.gtoreq.1.06. In a cross section of the lamp (the cross section of the arc tube is unshown for convenience), A (mm) represents the shortest distance between the arc tube and the inner tube along a line in a radial direction of the inner tube, and B (mm) represents a distance between the inner tube and the outer tube on a line segment C that is extension of the line.