An electron gun of in-line type for color picture tube including a pair of electrodes for an electrostatic focusing lens is disclosed. Each of the pair of electrodes has three electron beam passing holes arranged in line. Each of the electron beam passing holes is so shaped that the maximum dimension in the direction in which the electron beam passing holes are arranged in line is smaller than that in the direction perpendicular to the first-mentioned direction, and that the maximum dimension in the latter direction is larger than the center-to-center spacing between the electron beam passing holes. At least part of the electrode surfaces including the opening edges of the three electron beam passing holes is a curved surface, so that the distance between the surfaces of the pair of opposite electrodes is made different in value along each opening edge.