An apparatus includes a washing water supplying path connected to an ink chamber, including a seal blade and a doctor blade slidably contacting an outer circumference of an anilox roll; a washing water supplier for supplying washing water to an inside of the ink chamber through the washing water supplying path; a supplying path opening/closing device that opens and closes the washing water supplying path; a washing water recovering paths connected to the ink chamber; a suction recovering device that recovers the washing water in the ink chamber by suction through the washing water recovering path; and a controller that controls operations of the washing water supplier, the supplying path opening/closing device, and the suction recovering device. The control mode includes a decompression control mode in which the seal blade is elastically deformed towards the ink chamber by decompressing the inside of the ink chamber by recovering the washing water.