At least one of an upstream drive roller and a downstream drive roller is operated, after printing on web paper and at a time of transportation halt of the web paper, to make a tension value of the web paper between the upstream drive roller and downstream drive roller lower than a tension value at a time of transporting the web paper, so that at least part of contact portions of the web paper in contact with five cooling rollers separate from the five cooling rollers. Consequently, gaps can be produced between the contact portions of the web paper in contact with the five cooling rollers and the five cooling rollers. This can reduce waterdrops due to dew condensation adhering to the web paper. As a result, paper break can be inhibited at a time of starting transportation of the web paper.