A cathode ray tube capable of reducing a doming amount and suppressing an occurrence of moire stripes by providing protruding portions in a slot aperture of a tension type shadow mask. In a cathode ray tube including a mask frame formed in the form of a frame, and a shadow mask made of a flat plate containing a plurality of slot apertures, which is stretched and held onto the mask frame with a tension force applied in the longitudinal direction of the apertures, the shadow mask is provided with bridges linking the slot apertures arranged neighboring in the longitudinal direction, and the slot aperture is provided with protruding portions facing each other and protruding from the both ends in the lateral direction of the slot aperture into the inside of the slot aperture. Thus, it is possible to reduce the doming amount and to suppress an occurrence of moire stripes, while securing the mechanical strength and luminous intensity.