An electron gun for a color picture tube consists of a triode that generates a plurality of electron beams and a main lens which focuses and converges the electron beams. The main lens can be divided into two types, i.e., a pair of bi-potential focusing electron lenses and a combination of the bi-potential focusing electron lens and a uni-potential focusing electron lens. The electrodes constituting the main lens have apertures for permitting the transmission of a plurality of electron beams. The center axes of apertures are deviated toward the center axis of the embodiment of electron gun away from the axes of initial paths of the electron beams emitted from the triode.