The change from seniority-based and person-based systems towards performance-based and jobbased systems on individual reward determinations is one of the most significant changes in Japanese HRM over the last three decades. Centralized decision-making on HRM issues is also characteristic of Japanese HRM, and the seniority-based and person-based systems and centralized decision-making on HRM issues are complementary to each other. Therefore, the change towards performancebased and job-based systems can facilitate the change of centralized decision-making on HRM issues towards decentralized decision-making. This research investigated the extent to which senioritybased and person-based systems and centralized decision-making on HRM issues have changed. The method used for the investigation was a comparison between Japanese-owned companies and foreignowned companies operating in Japan. As a result, the research obtained some important findings, including the following issues. First, while the changes towards performance-based and job-based systems have progressed, there is no evidence on changes in centralized decision-making on HRM issues. Therefore, complementarity between the characteristics of Japanese HRM may have broken down. Second, although seniority-based and person-based systems have certainly changed towards performance-based and job-based systems in Japanese-owned companies, seniority elements are more focused in Japanese-owned companies than in foreign-owned companies, and performance and job elements are more focused in foreign-owned companies than in Japanese-owned companies. Third, it has been generally considered that shokumu suikou nouryoku (the ability to perform jobs) in Japanese HRM is general and abstract but not specific and that this characteristic of shokumu suikou nouryoku is complemented by a seniority-based system. Past research has found that Japanese HRM has changed towards the performance-based and job-based systems that characterize Western HRM, but that these changes are not yet complete, and Japanese HRM is in position midway between Japanese HRM and Western HRM. As a result, there have been debates concerning issues around person-based systems and job-based systems. In such situations, the factor analysis of the answers gathered from Japanese-owned companies conducted in this research extracted two factors: job and performance factors, which consist of shokumu suikou nouryoku, job value, role, performance and behavior (evaluated by competency); and seniority factors, which consist of age and years of service. It can be considered based on these results, that shokumu suikou nouryoku is no longer general and abstract, and it has changed towards having a similar characteristic of person specification extracted based on job analysis, which is due to the spread of Western HRM practices. The author argues that through the changing characteristics of shokumu suikou nouryoku, the characteristics of individual reward determination have qualitatively changed to be more similar to such determination found in Western HRM.