To provide a compact self-ballasted fluorescent lamp L where light flux build-up characteristic is improved even with an arc tube 3 where it is difficult to diffuse mercury vapor due to a smaller size.

By irradiating the direction of an irradiation aperture 4a with the light radiated from the arc tube 3 by a reflection film 4b, the illuminance directly under the lamp may be improved. Because many heat rays ejected from the arc tube 3 are not transmitted through the irradiation aperture 4a but reflected inside an globe 4 by the reflection film 4b, particularly towards the arc tube 3, a temperature of the arc tube 3 and an amalgam 6 rise quickly just after lighting, thereby improving the light flux rising edge characteristic.