The primary purpose of this study is to compare a specific characteristic of Ulhacha -printed books with Imitating Ulhacha-printed books to distinguish from each others. Ulhacha was made in the first year of King Secho (1455) used before Hideyoshi's Invasion of Korea in 1592, there are many kinds books printed with it. For this reason, Ulhacha used to printed books for long period, the letters were worn down and must be filled up with su n.0, pplementary letters during the reign of King Chungchong and Myungchong. And at the early times of King Suncho, Many letters were su n.0, pplement and printed many kinds of books very neatly. Ulhacha-printed books were classified four sorts of books according to its characteristic to examine closely. From the latter half of the 16th century, the beginning of King Suncho, what is called Imitating Ulhacha-printed book, many copies of book were printed off imitated with Ulhacha. Imitating Ulhacha-printed books also classified four kinds of books according to its characteristic. Being glance at imitated letters, they were similar to Ulhacha and confused one thing with another. To distinguish Ulhacha-printed books from imitated letter ones, it is important to discriminate each others. Generally speaking, imitating Ulhacha letters were resemblant Ulhacha closely, it is not easy to distinguish Ulhascha from imitated letter. But they have a tendency to exhibit more thin style than Ulhacha and different from its size. Out of Ulhacha-printed books, the big letters in Hunsa printed in the 7th years of reign of King Secho and Hangulcha in Kumgang panya paramil kyong samgahae printed in the 13th years of the reign of King Sung chong come in to question. Nevertheless the big letters in Hunsa is consider to be that of Ulhacha and Hangucha in Kumgang panya paramil kyong samgahae also to be Ulhacha mixed with Hang lcha, disagreement of opinions has been opted to give rise to problem. In order to verify such a problem, it is more convenient to use OHP film copied those letters than the naked eyes. As a result of collating with OHP film, the problem was proven to be above-mentioned.