This study analyzed the effects of prospector and defender strategies on cost asymmetry in the manufacturing industry in Korea and Japan. When a prospector strategy is adopted, the cost reduction is small by maintaining investment spending even if sales decrease by aggressively inducing market expansion and growth potential. On the other hand, when the defender strategy is adopted, the reduction in cost is larger because cost reduction and efficiency are emphasized to maintain the market. As a result of the study, first, Korea, which adopted a prospector strategy, showed a significant negative(-) value in the COGS when the sales of all manufacturing and material parts decreased. And in the non-material parts industry, a significant positive(+) value was shown. In Japan, only the COGS of material parts showed a significant negative (-) value. In other words, if the prospector strategy is implemented, Korea and Japan have a high proportion of internally procuring necessary resources in the materials and components industry, so even if sales decrease, surplus resources are not actively reduced, but maintained COGS level due to high adjustment costs. In the case of SG&A, in both Korea and Japan, the prospector strategy did not show any significant results when sales decrease. In the case of R&D expenditure, in both Korea and Japan, the prospector strategy did not show any significant results when sales decrease. Second, as a result of the defender strategy analysis, when the sales of only material parts in Japan decreased, the COGS and SG&A showed a significant positive(+) value, and it was not significant in Korea. In other words, compared to Korea, Japanese material parts, which implement a defender strategy, can be viewed as maintaining a cost advantage over competitors by reducing the COGS and SG&A to a very large proportion through active surplus resource adjustment when sales decrease. In the case of R&D expenses, only the material parts in Japan showed a significant negative(-) value when sales decreased, and it was not significant in Korea. Overall, when sales decreased, Korea reduces R&D expenditure relatively more compared to Japan. Even if it adopts a defender strategy, Japan is aggressive in R&D investment, so when sales decrease, R&D expenses are minimized as much as possible. This study is meaningful in that it verified the discriminatory cost behaviors by comparatively analyzing the effects of management strategies on cost asymmetry by comparative analysis of the material parts, non-material parts, and manufacturing industry in Korea and Japan. Furthermore, it implies that in order to respond to external environmental changes such as Japan's export regulations, internal factors such as business strategies must be considered. In addition, it can be used as basic data to determine the effects of government’ supportive policies and materiality on the business environment.