Glass tube for fluorescent lamp, fluorescent lamp, and lighting system

Disclosed is a glass tube for a fluorescent lamp that can realize a reduction in thickness of a bulb of a fluorescent lamp.  The glass tube for a fluorescent lamp comprises a tube body formed of a glass comprising 60 to 75 wt% of silicon oxide and 5 to 18 wt% of an alkaline earth metal oxide, a first film that is formed at least on the outer peripheral face of the tube body and is formed of at least one oxide selected from tin oxide, titanium oxide, zirconium oxide, and silicon oxide, and a second film that is stacked on the first film and is formed of a hydrophobic lubricant or a surfactant having an HLB value of not more than 13.