A support mechanism includes a support member which has a tab slidable along a groove, and can be fixed at a desired position when an engagement teeth array in the tab engages with an engagement hook. Also, a pressing member with a presser portion is movable along the engagement teeth array, and can be fixed at a desired position when an engagement hook engages with an engagement teeth array. Thus, a single front panel can be used for a number of flat display panels of different sizes.