An electrolytic capacitor and a ballast choke of a lighting circuit, are disposed on a first face of a circuit board facing a base, and a one-package switch of the lighting circuit is disposed on a second face, facing a fluorescent lamp. The one-package switch comprises field effect transistors contained in a single package and serve as two inverter switches for driving the fluorescent lamp. The one-package switch is a generally rectangular SMD with dimensions of not more than 6 mm respectively in length and width and mounted on the second face of the circuit board by means of terminals of the one-package switch. The one-package switch enhances heat dissipation properties of the circuit, enables the reduction of its dimensions, and increases the mounting efficiency.