An image-forming apparatus includes an electron source including one or more than one electron-emitting devices on a substrate, each electron-emitting device having a pair of oppositely disposed device electrodes, an electroconductive film connected to the pair of device electrodes and an electron-emitting region formed in part of the electroconductive film accompanied by a carbonaceous film which contains carbon or carbon compound as principal ingredient and is formed on and in a vicinity of the electron-emitting region, and an image-forming member for forming an image by emitting light when irradiated with electron beams emitted from the electron source. The electron source and the image-forming member are contained in a vacuum envelope, and an organic substance exists in the vacuum envelope to show a partial pressure of the organic substance greater than 1.times.10.sup.-6 Pa and a total pressure lower than 1.times.10.sup.-3 Pa. The organic substance is so selected that it shows a mean absorption time shorter than the drive period of the electron source.