To provide a new terphenoquinone derivative excellent in charge transport ability, compatibility with a binder resin, gas resistance, etc., and to provide an electrophotographic photoreceptor excellent in sensitivity properties and excellent also in aging stability of a photosensitive layer.

The terphenoquinone derivative is represented by formula (1). The electrophotographic photoreceptor is obtained by disposing a photosensitive layer containing the terphenoquinone derivative represented by the formula (1) on a conductive substrate. In the formula (1), R1-R6 are the same or different and each denotes alkyl group which may have a substituent or the like; and a and b each denotes an integer of 0-4.