An opening and closing assembly includes: (a) a first casing body; (b) a second casing body pivotable to be selectively placed in open and closed positions relative to the first casing body; and (c) a support stand for supporting the second casing body to maintain the open position. The support stand includes (c-1) a proximal end portion pivotably connected to one of the first and second casing bodies and (c-2) a distal end portion slidably connected to the other of the first and second casing bodies. The other of the first and second casing bodies includes (i) a guide portion for guiding the distal end portion of the support stand, and (ii) first and second wall portions cooperating with each other for gripping the distal end portion of the support stand. The distal end portion of the support stand includes a gripped portion having a thickness that is increased in a direction away from the distal end portion of the support stand toward the proximal end portion of the support stand.