A rectangular rear substrate which constitutes an envelope of an image display device is fitted with a reinforcing frame which reinforces the envelope. The reinforcing frame has a pair of first frame portions individually extending substantially parallel to long sides of the rear substrate and a pair of second frame portions extending substantially parallel to short sides of the rear substrate and connecting the first frame portions. Each of the second frame portions meets a relationship ΔH/H=13 to 33%, where H is a length of each long side of the rear substrate and ΔH is a distance between each short side of the rear substrate and each of the second frame portions.