Image forming apparatus having controller to control movement of pressing member for pressing the inner surface of transfer belt

An image forming apparatus comprising:

• an image forming portion configured to form a toner image;
• a rotatable endless belt configured to bear the toner image;
• a belt driving portion configured to drive the belt;
• a plurality of stretching rollers configured to stretch the belt, and including an inner roller and an upstream roller disposed upstream of and adjacent to the inner roller with respect to a rotational direction of the belt;
• an outer member disposed opposite to the inner roller via the belt and configured to form a transfer portion transferring the toner image to a recording material from the belt by contacting an outer circumferential surface;
• an outer member driving portion configured to drive the outer member;
• a pressing member contactable to an inner circumferential surface of the belt upstream of the inner roller and downstream of the upstream roller with respect to the rotational direction of the belt and capable of pressing the belt toward an outer circumferential surface side from an inner circumferential surface side;
• a moving mechanism capable of changing a pressing amount of the pressing member to the belt or a contacting and separating state of the pressing member to the belt by changing a position of the pressing member;
• and
• a control portion configured to control a ratio of a driving speed of the outer roller to a driving speed of the belt while the toner image is transferred to the recording material from the belt based on the position of the pressing member by the moving mechanism while the toner image is transferred to the recording material from the belt.