This study aimed to identify differences in the factors determining new product performance across countries through a comparative study of new product success factors in Korea, the United States, and Japan, and further to provide managerial implications for new product development for Korean firms. The results revealed that the factors generating differences in new product performance among the three countries include cultural factors, market maturity, competitive advantage in the new product development process, degree of market change, and intensity of industry competition. Specifically, in countries with strong collectivistic tendencies like Japan, internal environmental factors have a greater impact on new product performance, while in countries like Korea where the degree of social diversification is relatively low and the degree of market change is high, a firm's market orientation actually has a negative effect on new product success. In contrast, in the United States, where society is diversified and the degree of market change is small, a firm's market orientation was found to be the most important factor determining new product success. Furthermore, this study found that the most important new product success factor for Korean firms is not mere market orientation but rather superiority in the new product development process relative to competitors, which holds significant implications for most Korean firms that neglect the establishment of systematic new product development processes.