An image forming apparatus comprising: an image bearing member configured to bear a toner image; an image forming portion configured to form the toner image on said image bearing member; an endless belt onto which the toner image formed on said image bearing member is transferred at a primary transfer portion; a plurality of stretching rollers (22, 24, 25a, 25b, 26, 29) including an inner roller and configured to stretch said endless belt; an outer roller configured to form a secondary transfer portion, in cooperation with said inner roller, where the toner image is transferred from said endless belt onto a recording material; a position changing mechanism configured to move said inner roller to change a position of the secondary transfer portion with respect to a circumferential direction of said inner roller, wherein said position changing mechanism is capable of changing a position of said inner roller to a plurality of positions including a first position and a second position positioned downstream of the first position with respect to a rotational direction of said endless belt; a feeding member configured to feed the recording material to the secondary transfer portion; and a feeding member driving portion configured to drive said feeding member; characterized by a controller configured to control a time difference from a predetermined reference timing to a feeding start timing of the recording material by said feeding member, wherein in a case that the toner image is transferred onto the recording material in a state in which said inner roller is in the first position, said controller controls the time difference so that a value obtained by dividing the time difference by a driving speed of said endless belt during transfer becomes a first predetermined value, and in a case that the toner image is transferred onto the recording material in a state in which said inner roller is in the second position, said controller controls the time difference so that the value obtained by dividing the time difference by the driving speed of said endless belt during transfer is a second predetermined value different from the first predetermined value. an image bearing member configured to bear a toner image; an image forming portion configured to form the toner image on said image bearing member; an endless belt onto which the toner image formed on said image bearing member is transferred at a primary transfer portion; a plurality of stretching rollers (22, 24, 25a, 25b, 26, 29) including an inner roller and configured to stretch said endless belt; an outer roller configured to form a secondary transfer portion, in cooperation with said inner roller, where the toner image is transferred from said endless belt onto a recording material; a position changing mechanism configured to move said inner roller to change a position of the secondary transfer portion with respect to a circumferential direction of said inner roller, wherein said position changing mechanism is capable of changing a position of said inner roller to a plurality of positions including a first position and a second position positioned downstream of the first position with respect to a rotational direction of said endless belt; a feeding member configured to feed the recording material to the secondary transfer portion; and a feeding member driving portion configured to drive said feeding member; characterized by a controller configured to control a time difference from a predetermined reference timing to a feeding start timing of the recording material by said feeding member, wherein in a case that the toner image is transferred onto the recording material in a state in which said inner roller is in the first position, said controller controls the time difference so that a value obtained by dividing the time difference by a driving speed of said endless belt during transfer becomes a first predetermined value, and in a case that the toner image is transferred onto the recording material in a state in which said inner roller is in the second position, said controller controls the time difference so that the value obtained by dividing the time difference by the driving speed of said endless belt during transfer is a second predetermined value different from the first predetermined value.