This study tried to reveal the relation among the necessary and sufficient conditions of human relation, which is the core concept of human-centered counseling. The relation of these three conditions are quite different according to what we take as the main content of authenticity. If we take congruence as its content, as Rogers did in his early academic years, three conditions are equal in their importance as instruments which counselor can use. But, if we take presence as its content, as Rogers did in his later academic years, authenticity possesses central position while using empathy and unconditional positive regard as its instruments. In this relation, we can say authenticity is a continuous growing process of self realization. And it also can be sad that the three necessary and sufficient conditions compose productive counseling relation inviting both counselor and client to the self realizing process.