In 2007, townhouses became popular among wealthy professionals in the age group of 40 to 50 years who wanted a unique residence in a rural area. However, the townhouses were not selling because they were located outside the city and were highly priced and even maintenance costs were expensive. Consequently, townhouse prices were continuously decreasing, prompting a change in the townhouse market environment due to miniaturization and real demand rather than investment value. This case study analyzes a stagnant townhouse market wherein market changes prompted unsold townhouses to be successfully sold. It studies the business plan, site acquisition, financing, licensing, and the 4P(place, price, product, promotion) marketing mix, which focuses on location selection, pricing, product development, sales and promotion, of “The K Construction Company”’s “Maison Forest” development project. In addition, it presents the profit and loss analysis conducted during the actual development process, the decisions and problems the company faced, and the solution devised to address them. During the real estate development project process, it is difficult to make decision or solve problems in terms of architecture and academic real estate. Through this case study, necessary key points, process, and understanding of a successful townhouse development project are suggested. This case study makes an educational contribution for improving the capabilities of developers and workers of the real estate industry in the future. We hope that the townhouse, as a practical and eco-friendly residential product, might become a solution for a more efficient housing supply to people suffering from housing shortage and contribute to the creation of a new housing culture and national housing supply policy.