PURPOSE: To obtain excellent printing quality, by tightly closing an inking room, controlling the internal temperature at a specified value, thereby maintaining the physical characteristics of the printing ink at a constant level.

CONSTITUTION: The inking room 8 is composed of an inking arrangement, a dampening arrangement 7, and various rollers. The room 8 is tightly closed by a shielding cover 9 made of transparent synthetic resin (symbol 1 is a plate cylinder, 2 is a rubber blanket cylinder, 3 is an imperession cylinder, and 4 is a combining device), and controls the internal temperature at the specified value. Namely, the temperature in the inking room 8 obtained by performing the measurement by a sensor 13 is compared with a preset temperature by a comparator 4. When the difference is obtained, a cooling means 10 of a constant temperature device 16 is operated through a control device 15 by using the obtained difference signal. Air is circulated through the sequence of the constant temperature device 16, air supplying duct 11, the inking room 8, and air exhausting duct 12, thereby cooling the inking room 8 so as to obtain the preset temperature.