To reduce the humidity of the inside of a plate cylinder forcedly to eliminates effects of the humidity of the inside of the plate cylinder.

In a stencil printer 100, an ink roller 10 supplying an ink to the stencil master 1 rolled around the drum-shaped outer periphery of a mounted plate cylinder 7 is arranged in the plate cylinder 7. The stencil printer 100 is provided with a drum shaft 8 having a first ventilation possible hollow part 8c and serving as a shaft member supporting the plate cylinder 7 in a rotatable way, air suction/discharge fans 30 and 32 serving as supply and discharge means of blowing air into the first hollow part 8c forcedly and supplying air to and discharging air from the inside of the plate cylinder 7 and an air discharge outlet 8a or an air supply inlet 8e so as to supply outside air to the inside of the plate cylinder 7 and thereby reduce the humidity of the inside of the plate cylinder 7 forcedly or keep the humidity constant.