A glass bulb for a cathode ray tube comprising a panel portion having a substantially rectangular face portion and a funnel portion having a neck portion, wherein when the glass bulb is used for a cathode ray tube, the glass bulb at least regionally suffers from a tensile stress resulting from the atmospheric pressure on the outer surface of the glass bulb having a vacuum inside, at least part of the face portion of the panel portion where the tensile stress over the face portion has a maximum value &sgr;VP has a compressive stress layer formed by chemical tempering on the outer surface, and the &sgr;VP, the magnitude of the compressive stress on the compressive stress layer &sgr;C MPa, and the thickness of the compressive stress layer tC &mgr;m satisfy the following relationship: 120/tC≧(1−|&sgr;VP/&sgr;C|)>30/tC provided that &sgr;VP≧20 MPa.