An internal magnetic shield includes a pair of opposing long side walls (1), a pair of opposing short side walls (2), and an opening (3) enclosed by these side walls in the center. The short side walls (2) are provided with notches (4) having a substantially home-plate shape. This configuration can reduce mislanding of an electron beam on the entire screen and easily balance the amount of mislanding due to geomagnetism in the tube-axis direction and in the horizontal direction perpendicular to the tube axis. As a result, a cathode ray tube capable of displaying images without displacement and unevenness of colors can be provided.