This study examines the effect of patent acquisition and design registration on firm value, sales, and costs. Especially, using a structural equation model(PLS), the paper investigates a mediating role of sales and costs on stock price of the firm. For empirical investigation, we use 544 sample of patent acquisitions and 599 sample of design registrations filed in DART(Data Analysis, Retrieval and Transfer System) and KIPRIS(Korea Intellectual Property Rights Information Service) over the period of 2001- 2005. We measure the change of firm value as cumulative abnormal return(CAR), and the changes of sales and costs as abnormal sales growth(ASG) and abnormal cost growth(ACG), respectively. In addition, our paper uses financial status variables such as intangible asset ratio, market-to-book ratio, company size, debt ratio, advertising expenses, R&D expenditure, ROA, and listed market. Empirical results show that stock price reactions to the announcement of patent acquisition and design registration are positive and significant, and the reactions are more positive in patent acquisition. This implies that the firm value increases from both patent acquisition and design registration. Furthermore, we search factors or conditions under which the firm value increases by using multiple linear regressions. The firm value in the case of patent acquisition increases as the firm has lower market-to-book ratio and is listed in KOSDAQ, while the firm value in the case of design registration increases as the firm has more intangible assets and higher profitability. In addition, we find that ASG is significantly positive and ACG is significantly negative for the firms that announce patent acquisition and design registration. The mediating role of ASG and ACG on firm value is investigated by PLS. The results show that the effect of patent acquisition on firm value is mediated by ASG, while the effect of cost reduction on firm value is not statistically significant. When we compare patent acquisition with design registration, patent acquisition makes a larger cost reduction. Also, the overall effect (including indirect effect) of patent acquisition compared to design registration on firm value is significantly larger, even though the direct effect on firm value is not significantly larger. This study is expected to help foster inter-disciplinary research in that we consider the mediating role of sales and costs in analyzing the effect of patent acquisition and design registration on firm value. Sales and costs play the role of bridge points between business strategy and firm value, in order to find out a path from business strategy to firm value. Another contribution of this paper is that we employ financial accounting data instead of judgment data that has been used in Marketing and Business Strategy research. However, this paper has limitations due to data unavailability. For example, we were unable to utilize more specific information on patent acquisition and design registration in the cross-sectional analysis of CARs. In the follow-up research, we will further examine whether the firm’s public relations associated with patent acquisition and design registration have any differential effect on firm value.