This invention provides an electrophotographic photoreceptor, which has excellent electric characteristics and, even when repeatedly used for a long period of time, can stably form good images having a high resolution and a good quality, and an electrophotographic photoreceptor cartridge using the electrophotographic photoreceptor and an image forming apparatus. The electrophotographic photoreceptor is an electrophotographic photoreceptor for use in an image forming apparatus, comprising an electrification part for electrifying an electrophotograpic photoreceptor, an exposure part for exposing the electrified electrophotographic photoreceptor to form an electrostatic latent image on the electrophotographic photoreceptor, and a developing part for developing the electrostatic latent image.The electrophotographic photoreceptor is characterized in that the electrophotographic photoreceptor comprises an electroconductive support and a photosensitive layer, the photosensitive layer contains a compound represented by formula (1), the exposure part comprises an LED, the resolution of the electrostatic latent image is not less than 1200 dpi, and the average circularity of a toner as measured with a flow-type particle image analyzer is 0.94 to 1.00 when the electrostatic latent image is developed with the toner, or the image forming apparatus is a full-color tandem system. [Chemical formula 1] (1) wherein R1 and R2 each independently represent an organic group having not more than 30 carbon atoms; and X represents a saturated hydrocarbon group having not less than 3 and not more than 30 carbon atoms.