A developing cartridge includes a developing roller, wherein a bias voltage is capable of being applied to the developing roller; and a developer-side electrode portion that is electrically connected with a shaft member of the developing roller, wherein the developer-side electrode portion is positioned at the bottom of the developing roller in order to apply the bias voltage to the developing roller, and the developing cartridge is capable of being mounted to an image holding body cartridge with an image holding body that holds a developing agent image formed by a development of an electrostatic latent image.