Image forming apparatus having two transfer units

An image forming apparatus comprising:

• a first image forming unit that includes a first image holding member and a first developing unit, the first developing unit accommodating a first developer that includes a first toner and a first carrier and developing an electrostatic charge image formed on a surface of the first image holding member using the first developer to form a first toner image on the surface of the first image holding member;
• a first transfer unit that transfers the first toner image formed on the surface of the first image holding member to a transfer medium;
• a second image forming unit that is disposed downstream of the first image forming unit in a traveling direction of the transfer medium and includes a second image holding member and a second developing unit, the second developing unit accommodating a second developer that includes a second toner and a second carrier and developing an electrostatic charge image formed on a surface of the second image holding member using the second developer to form a second toner image on the surface of the second image holding member;
• and
• a second transfer unit that transfers the second toner image formed on the surface of the second image holding member to the transfer medium to which the first toner image is transferred,
• wherein a volume resistivity of the first carrier is higher than a volume resistivity of the second carrier, and
• a volume average particle diameter of the first carrier is more than a volume average particle diameter of the second carrier.