A transfer roller lies opposite to a supporting roller across an image carrying belt and abuts against the outer surface of the image carrying belt to form a transfer nip. A driving force transmission unit transmits driving force from a driving source to a driving roller. A drive control unit performs drive control of the driving source. A feedforward control unit performs feedforward control on the driving source via the drive control unit. An entry detecting unit detects entry of a sheet in the transfer nip. The feedforward control unit considers an entry detection signal output by the entry sensor as a trigger for performing feedforward control after a predetermined time.