To uniformize an electron emitting characteristic in an image forming device provided with a display panel having an electron source having plural electron emitting elements, an image forming member and a spacer.

In an activation process for increasing an element current and an emission current by accumulating carbon or a carbon compound by impressing a voltage pulse between element electrodes of electron emitting elements for forming an electron emitting part in an organic substance atmosphere, electron emitting efficiency is uniformized by controlling the element current of the respective elements by changing activation time with every element in response to a distance from a spacer.