Traditionally, under the Korean Patent Law, the test for non-obviousness of an invention has merely required a simple comparison of prior arts and an invention at the issue in light of the purpose, structure, and effect without clear and objective criteria for both factual and legal inquiries. In contrast, the EPO has developed the problem-solution approach and would have been approach to determine the inventive step, while the U.S patent Law has made a significant change to the TSM test through the KSR. v.Teleflex case. Fortunately, the Supreme Court and the Patent Court have recently addressed more specific criteria for assessment of non-obviousness. The Supreme Court made it clear that they may not read into prior art the teachings of the invention in issue in determining whether it would have been obviousness at the time the invention was filed to a person having ordinary skill in the pertinent art in its decision of 2006hu138. This decision is the first case the Supreme Court explicitly mentioned impermissible hindsight bias. And in its decision of 2005hu3284, the Supreme Court held that to determine the question of obviousness for an invention that combined old elements, the court should consider; (1) suggestion, motivation in prior arts as well as other objective indicia such as (2) state of art when patent application was filed, (3) trend of technology development, and (4) long-felt need for invention. In its decision of 2006hur6099, the Patent Court took a position similar to the EPO’s problem-solution approach and held that the court must find the differences between the subject matter sought to be patented and the prior art are such that the matter as a whole would have been obvious. Even though each of above cases has addressed the non-obviousness standard from a different angle, the underlying ideas suggest that the Supreme Court will provide more objective criteria that guarantee the uniformity and predictability of the non-obviousness determination sooner than later.