Nowadays, the human resources of an organization are very important in order to survive in competitive business environment. This study investigates the influence of four decision-making styles in Myer-Briggs Type Indicator (MBTI) and working conditions on organizational effectiveness. Job satisfaction and immersion have been regarded as key conceptions of organizational effectiveness. The result of this study has shown that organizational effectiveness are influenced by personality types and working conditions. Based on the result, an enterprise must provide working conditions which are conducive and suitable for all decision-mak- ing styles. For ST-type, the composition of good relationship with superiors, clear organization’s visions and goals and rewarding compensation on original idea contribution need to be provided. On the other hand, autonomic authority and job assistance in co-worker are more suitable for NT-type. Finally, in the case of SF-type, the organization must give job assistance in co-worker.