A conveying device includes a plurality of conveying rollers supported in parallel at predetermined intervals, and conveys a workpiece to a heat-retaining/heating furnace from a rolling mill by the conveying rollers. The conveying device includes an impact prediction data collecting unit and a control unit. The impact prediction data collecting unit acquires data on the upstream of the heat-retaining/heating furnace. The data is used to predict the magnitude of an impact applied to rollers in the furnace, which are positioned in the heat-retaining/heating furnace, of the conveying rollers by the workpiece. The control unit predicts the magnitude of an impact from the data, which is acquired by the impact prediction data collecting unit, and adjusts the conveying speed of the workpiece in the heat-retaining/heating furnace according to the magnitude of the impact.