This study examines the interpretation of key terms in Article 7, Paragraph 1, Subparagraph 1 of the Enforcement Decree of the Patent Act, focusing on Supreme Court Decision 2021Hu11070 from July 25, 2024. This judgment established a standard by interpreting “pharmaceutical efficacy” as the indication, “active part” as the active moiety, and “active component” as the active ingredient. Accordingly, this study proposes interpreting the meaning of “substances with a novel chemical structure” in Subparagraph 1 in accordance with the purpose of the term extension system, while considering cases where an invention’s implementation is restricted due to complex licensing procedures. Based on pharmaceutical classification by the Ministry of Food and Drug Safety, new drugs are considered eligible for extension registration applications, generic drugs are excluded, and only a portion of data submission drugs are included. Overall, this interpretation emerges as significant because it fills the gaps in interpretation while ensuring consistency with the systems of major countries and existing precedents.