A pair of magnetic bodies (33a, 33b) extending in an axial direction of a color cathode ray tube are arranged apart from each other in a direction perpendicular to the axial direction so as to shield an external magnetic field acting on three electron beams forming a row in the direction perpendicular to the axial direction. A ring-like 6-pole magnet plate (30) disposed in a plane perpendicular to the axial direction is arranged in substantially a central region in a longitudinal direction of the magnetic bodies. These 6-pole magnet plate and magnetic bodies arranged in the particular positional relationship generate a magnetic field distributed to have a plurality of peaks of intensity on the orbit of the central beam. The magnetic field runs on the orbit of the central beam toward one magnetic body around one of the peaks, and runs toward the other magnetic body around the adjacent peak. The cathode (46) is positioned intermediate between the second and third peaks of the magnetic field intensity as counted from the side of a panel. The particular construction makes it possible to decrease the magnetic field component acting on the central beam without decreasing the magnetic field components acting on both side beams. As a result, the central beam is prevented from an undesired moving.