Provided is an automatic washing device which enables thorough washing of an anilox roll that has been used in a printing job. A printing plate 3 is installed on a plate cylinder 2. The plate cylinder 2 transfers printing liquid via the printing plate 3 onto a substrate 15 placed on a printing platen 14. An anilox roll 1 rotates in synchronization with the plate cylinder 2 so as to apply the printing liquid to the printing plate 3. A coating part 4 forms a liquid trap 5 by coming into slide-contact with the anilox roll 1 during printing and during washing out of the printing liquid using a washing liquid, applies a coat of the printing liquid, washes out the printing liquid after printing, and then is separated from the anilox roll 1. A liquid supply part 6 supplies the printing liquid to the liquid trap 5 during printing, and supplies the washing liquid to the liquid trap 5 during the washing after the printing. Following the washing of the anilox roll 1, a pure water supply part 8 supplies purified water to
