At the start of paper conveyance, a gate is turned upwards to a first position to thereby close a sixth conveying path and establish communication between a first conveying path and a second conveying path so that the paper having passed through a fixing unit starts to be conveyed from first conveying path to second conveying path. At the same time, air is exhausted from an exhausting mechanism arranged upstream of a cooling mechanism. When a first paper sensor detects the leading end of the paper, a cooling fan starts to rotate at a predetermined rotational rate to start blowing air at a predetermined volume of cooling airflow.