PURPOSE: To efficiently obtain a cathode ray tube bound with a explosion-proof band including a give clamping force by locating the cathode ray tube on a measuring device provided with stoppers for determining positions in a horizontal direction and in the vertical direction and by measuring the volume of deformation in the center portion of the cathode ray tube panel.

CONSTITUTION: Four stoppers 32W35 for determining position in the vertical direction by supporting each corner in the cathode ray tube panel are provided on the flat surface of the top 30, and further respective stoppers 36W38 for determining position in a horizontal direction of the cathode ray tube are provided on three rod portions 31 projected from the side of the top, and furthermore a measuring contact terminal 41 of a dial indicator 40 provided is projected into the throughole 39 provided in the central portion of the top. A cathode ray tube 50 before the explosion-proof processing is mounted on a measuring device 51 and the value in the dial indicator is read. Next, the cathode ray tube after the explosion-proof processing is mounted on the measuring device again and the value in the dial indicator is read.