A solid laser comprises an anisotropic laser crystal, to which a rare earth element has been added, a pumping device, which causes a pumping beam to impinge upon the laser crystal, and a resonator mirror, which oscillates a solid laser beam having been produced by the laser crystal. The laser crystal is located in an orientation such that its crystallographic axis may makes an angle with respect to a laser oscillation axis. A device linearly moves the pumping means with respect to the laser crystal and the resonator mirror such that only either one of ordinary rays and extraordinary rays, which are produced by the laser crystal, may oscillate selectively, or a device linearly moves the resonator mirror with respect to the laser crystal and the pumping means such that only either one of ordinary rays and extraordinary rays, which are produced by the laser crystal, may oscillate selectively. A single desired beam radiation line is thus selected easily.