Abstract-The present era of globalization and technology have encouraged the human resource management (HRM) function to optimize strategy in dealing with challenges faced by the organization. With precious value and endless capabilities, the contribution of capable human resources practices is needed to support the strategic objectives of the company. In a sense of developing a broader organizational climate through the program people capability as a source of sustainable and highly competitive advantage in the organization, the progression of extra-role behavior activities has been developed in the form of supporting interactions and relations among employee and employers by helping each work unit running in the company more effectively. This study attempts to propose and analyze the effects of HRM practices on organizational citizenship behavior (OCB). The HRM practices variable were measured through the High-Involvement HRM Practices tool by Prieto and Pérez-Santana (2014), while the OCB variables were measured based on five major dimensions by Organ (1988). The analysis is on the active employees of PT Sigma Cipta Caraka (Telkomsigma) who had worked for at least a year in the company with the number of 243 employees. This study uses quantitative methods in collecting data with a questionnaire as a research instrument. The research data will be analyzed using descriptive statistic analysis, correlation, and regression analysis to test the relationship among variables. The results of this study provide an evidence that each dimension of HRM practices, with the exception of training, have a positive significance but no strong indication to encourage OCB activities showed by employees in the ICT company.