PURPOSE: To provide a fluorescent lamp and a glass tube for it, which has non-circular cross-section, presents excellent strength and illumination efficiency, and can easily be embodied through utilization of a conventional molding facility.

CONSTITUTION: Recesses mating with each other are furnished as stretching in the longitudinal direction of a glass tube, so that it is equipped with an excellent strength compared with a conventional glass tube having elliptical cross-section, and the emitted light amount to the side-face on long dia. side of the cross-section increases. This can easily be embodied through continuous molding by utilizing an existing manufacturing facility for a glass tube having circular cross-section, which allows suppressing the cost and enables stable supply. By the use of these recesses, phosphors having different central light emission wave-lengths are applied to two regions in the glass tube partitioned by the recesses to permit manufacturing fluorescent lamps or the like wherein a single lamp can emit two colors simultaneously.