The purpose of this research was to examine exploratively the process of social contagion and other factors affecting achievement motivation of young adult workers in the workplace, focusing on "selffulfillment achievement motive" and "competitive achievement motive". An interview investigation was undertaken with 8 adults working for companies, and also a multi-stage path model was proposed, analyzing the questionnaire responses of 355 people. Major findings were as follows: (1) "inference of self-fulfillment achievement motive of a colleague" had a direct impact on "change in self-fulfillment achievement motive", and "inference of competitive achievement motive of a colleague" had a direct impact on "change in competitive achievement motive"; (2) Through a "recognition of reference power of a colleague"and "reaction to achievement motive of a colleague", "inference of achievement motive of a colleague" had an indirect impact on "change in achievement motive"; (3) "inference of self-fulfillment achievement motive of a colleague" had a positive impact indirectly on "change in two aspects of motive", and "inference of competitive achievement motive of a colleague" had a negative impact indirectly on "change in two aspects of motive".
