Globalization, advances in information technology and many other factors demanded that organizations should adapt to the changing business environment, by making practices more efficiently, and more focusing on meeting customers' new needs. On the way of transforming organizations towards this direction, employees' proactive behavior such as taking change behavior and voice behavior are more required for organizational change and innovation. Employees' role in the process of organizational transformation is very important. In spite of its practical importance, there is little empirical research on the employees' taking charge behavior and voice behavior. In this view point, the antecedents of employees' taking charge behavior and voice charge behavior are explored in this study. In order to conduct a focused investigation, we begin with the influence of leader-member exchange on the aforementioned two behaviors, since both theoretical and empirical support has been established on that. And then we also investigate the influence of psychological safety. In particular, employees' psychological safety is explored as a mediating variable in the relationship between leader-member exchange and taking charge behavior and voice behavior. On the basis of theoretical linkages among these constructs, a conceptual model with several hypotheses are proposed. Empirical data were collected by using a set of questionnaires. This survey was administered to employees who are currently working in 32 major firms with various industries including electronics, IT, machinery, finances, service, distribution and transportation. Survey participants were randomly selected. Respondents were briefed with the purpose of the study beforehand. Sufficient time was given to themso that accurate responses could be collected. Completed surveys were returned directly to us in sealed envelope by mail. Due to missing data, 213 dyads(426 respondents) were used for the analysis. Confirmatory factor analysis for the validity test and Cronbach's alpha test for the reliability test were conducted. Moreover, structural equation modeling(SEM) was employed to test the hypothesized relationships in the conceptual model. Results show that the proposed model has a resonable fit to the data. From these analyses, we can find some significant findings and implications. First, the quality of leader-member exchange has a positive impact on employees' psychological safety. Second, employees' psychological safety has positively impact on their taking charge behavior and voice behavior. Third, employees' psychological safety has mediating effects on the relationship between the quality of leader-member exchange and employees' taking charge behavior, as well as employees' voice behavior. Implications, future research directions, and limitations of this study are also discussed.