While the effects of mindfulness practices on the self are not widely recognized, a reduction in self-centered or “self-referential” processing stands as one of the central therapeutic mechanisms of mindfulness-based psychotherapy. In this literature-based research, I compared two cultural variations of mindfulness-based psychotherapy: Mindfulness-Based Cognitive Therapy (MBCT), developed recently in the West, and Morita Therapy, founded in Japan during the 1920’s based on Zen Buddhism. Despite the vast cultural/historical gap between them, they are strikingly similar in a number of respects. The most significant similarity is that they both use mindfulness as their primary therapeutic means; both, in turn, involve a change in the conception of ‘self’ via mindfulness. Despite the remarkable similarities, there are also discrepancies in their philosophies, methods, and techniques, which likely arose from the difference between the western individualistic and eastern collectivist values. Throughout this thesis, I show that the self can be understood as a two-layered structure. There is an inner layer—the operating locus of mindfulness—that function similarly irrespective of culture context, which may be responsible for some of the similarities between the therapies. There is also an outer layer that varies across cultures—a possible source of the differences in the therapies.