Image forming apparatus that regulates developing agent and applies regulatory bias

An image forming apparatus comprising:

• an image bearing member;
• a latent image forming portion that forms a light portion potential and a dark portion potential on a surface of the image bearing member and thus forms an electrostatic image on the image bearing member;
• a storage chamber storing a developing agent;
• a developing agent carrying member that comes in contact with the image bearing member and develops the electrostatic image formed on the image bearing member using the developing agent;
• a regulating member that regulates the developing agent that the developing agent carrying member carries to develop the electrostatic image;
• and
• a regulatory bias application portion that applies a regulatory bias Vb to the regulating member,
• wherein the developing agent in the storage chamber includes a toner containing a toner particle, organosilicon polymers covering the surface of the toner particle, and a metal soap,
• wherein the amount of water-washing migration of the organosilicon polymers is 0.20 mass % or less,
• wherein the Martens hardness of the toner measured in a condition of a maximum load of 2.0×10-4 N is at least 200 MPa and not more than 1,100 MPa,
• wherein a peripheral speed ratio of a peripheral speed of the developing agent carrying member to a peripheral speed of the image bearing member, has a range of 120% to 300%, and
• wherein a dark portion potential Vd on the surface of the image bearing member and the regulatory bias satisfy the relationship of Vd<Vb.