Image forming apparatus

An image forming apparatus for forming an image on a recording material, comprising:

• a rotatable first image bearing member;
• a plurality of rotatable second image bearing member;
• an endless belt provided rotatably opposed to said first image bearing member and said second image bearing members;
• a driving roller for rotating said belt member in contact with an inner peripheral surface of said belt member;
• a supporting roller for supporting said belt member in contact with the inner peripheral surface of said belt member;
• a first transfer member provided opposed to said first image bearing member via said belt member;
• a plurality of second transfer members provided opposed to said second image bearing members, respectively, via said belt member;
• and
• a supporting member for movably supporting said second transfer members, wherein said supporting member is movable between a first position in which said second transfer members are placed in a state in which said second transfer members are contacted to said belt member together with said second image bearing members to sandwich said belt member therebetween, and a second position in which said second transfer members are retracted from the first position to space said second image bearing members and said second transfer members from said belt member,
• wherein when image formation is effected in a state in which said supporting member is positioned in the first position, a nip between said first image bearing member and said belt member is positioned closer to a side where said supporting roller is positioned than a rectilinear line connecting contact positions of said belt member with said second image bearing members.