Understanding and study of resentment are still outside the framework of scientific psychology to a significant degree that cannot be considered as reasonable. It is difficult to find in human life a more meaningful and widespread phenomenon that coexists with all our contacts and continually working upon one’s attitudes, emotions and decisions. The objective of this article is the introduction of this topic to the subject of scientific psychology and even if to a small degree to fill the above void in psychology. To introduce resentment in the scientific field, the data on the study of forgiveness was used, which is perceived as an antipode of resentment and can help in the understanding and study of resentment as well as the study of unforgiveness that is much closer to the phenomenon of resentment.