An envelope includes a first substrate having an image display surface, and a second substrate opposing the first substrate with a space therebetween. Electron sources for activating the image display surface are arranged on the second substrate at a predetermined pixel pitch in an X-direction and a Y-direction perpendicular to each other. Spacers are provided between the first and second substrates. The spacers are arranged at several times the pixel pitch in the X-direction, and arranged in the Y-direction at the same pitch as the pixel pitch at least in a part of the image display surface, those of the spacers arranged in the Y-direction being arranged in line with the electron sources and being located at both sides of each of the corresponding electron sources to make an electron emitted from each of the corresponding electron sources pass between each adjacent pair of those spacers.