Diocesan bishop is constituted as a shepherd of the particular Church. As a successor of Apostles, he has to watch over, devolve deposit of faith, totally truly teaching of Jesus Christ. He also has to sanctify and preside over his community. The aim of the article is to answer a question: what competences has the diocesan bishop in performing his authority and in which way this competences are accomplishing? At the beginning the Author analyzed the concept of the institution of diocesan bishop. Then he analyzed the concept of nature and function of the authority of diocesan bishop. The last stage was to analyze the concept of the competence and to show different kinds of competence.