A self-ballasted fluorescent lamp capable of achieving a similar appearance to that of an electric light bulb for general illumination includes a base that is attached to a bottom end of a cover and a luminous tube that is supported at a top end of the cover. Electronic components forming a lighting circuit are mounted on a substrate. The substrate is formed to have such a width dimension that allows the substrate to be inserted into the base. The substrate is vertically disposed along a center axis of the base at a position offset from the center axis. Large electronic components are disposed on a first face of the substrate, which faces a large component area in the base formed by the offset substrate.