In a flat type image forming apparatus formed by electron emitting devices, the invention is to provide a light emitting substrate, capable of relaxing influence of an abnormal discharge on the electron emitting devices. On a glass substrate 1, a resistor member 4 extending in X- and Y-direction, and a black member 6 extending in X- and Y-directions are formed. Phosphors 5 are positioned in apertures of the black member 6, and are covered by metal backs 7 divided in X- and Y-directions. The metal backs 7 and the resistor member 4 are electrically connected through the black member 6, and the resistance between the metal backs 7 is defined by the resistor member 4 in the Y-direction in which the adjacent metal backs 7 have a wider gap than in the X-direction.