To provide a deflection yoke and socket mounting mechanism of a cathode-ray tube automatically adjusted for a cathode-ray tube to be tested of different size and without requiring replacement every size.

This mounting mechanism comprises a yoke loading part 4 at which a downward deflection yoke 2 is loaded on a large diameter side, a socket holding part 9 at which a socket body 3 is held on a plug-in side, and a link part 5 at which the socket holding part 9 holds and disposes the yoke loading part 4 and the socket holding part 9 with given intervals, the deflection yoke 2 being mounted to a funnel part 1F during mounting to a cathode-ray tube 1, the socket body 3 being plugged in a stem pin 1P. In this case, an expandable position adjusting members 9 and 11 are provided axially at the link part 5, when the socket body 3 is plugged in the stem pin 1P the position adjusting members 9 to 11 are automatically expanded and contracted corresponding to the size of the cathode-ray tube 1, and an interval L' between the deflection yoke 2 and the socket body 3 is automatically adjusted.