Due to the fact that nurses may deal with diverse populations in the work place, it is very important for then to maintain appropriate interpersonal relationships with clients. Nurses should maintain diverse types of relationships appropriately with patients with special needs and their families during crisis, other nursing colleagues and staff on the same team, clients in the school or work place as well as the community. In particular, a hospital is a society with a system and hierarchy, and the importance of interpersonal relationships is much more emphasized. In interpersonal relationships, it is very important for a person to communicate with others in an accurate manner, and when the communication is not achieved appropriately, the person may have troubles and experience distress and conflicts because of the inaccurate communication of thoughts. According to the findings of previous studies, nurses actually experience much distress in the work place because of the miscommunication that they have with others. The purpose of this study was to observe a correlation between Myers-Briggs Type Indicator and assertiveness behavior, and to exam the effects of assertiveness training on the assertiveness behavior and conflict management mode. The subjects of this study included 20 persons in the experimental group and 20 persons the in control group. Myers-Briggs Type Indicator was applied before the study. The assertiveness training group received six, 120 minutes sessions over a 3 week period. Pre-test on assertiveness behavior, Communication Conflict Inventory-General, Role Conflict Inventory- General, Conflict Management Mode was achieved for all the subjects prior to the training. Post-test was administered to all the subjects one week following the last session. The data were analyzed using SPSS PC program to obtain findings on mean. standard distribution, t-test, and Pearson correlation. The results are as follows: (1) Myers-Briggs Type Indicator Introvert/Extrovert was correlated to assertive behavior and avoid- response type conflict management mode. (2) The assertiveness training was correlated to assertiveness behavior, communication conflict degree, and avoid- response type conflict management mode. (3) The post-test scores between the training group and the control group were significantly different in assertiveness behavior and avoid-response type conflict management mode. It is suggested that more studies need to be done to differentiate the effects of Myers-Briggs Type Indicator and assertiveness training on assertiveness behavior and avoid-response type conflict management mode.