Öz
Custody is a type of legal representation. The issue of who will have the right of custody may vary according to different possibilities. However, the right of custody, as a rule, belongs to both parents who are married to each other. One of the most important issues that arise, especially in case of divorce, is determination of who will have custody. Once this is determined, new substantial change in circumstances may occur. For example, mother or father may marry someone else, move to another place, die, or fail to fulfill personal relationship arrangement. In such a case, judge has authority to adapt to changing conditions in terms of child custody, personal relationship and child support within the scope of divorce provision. Thus, it is possible to change the person who has custody. Judge may decide on it at request or ex officio. In order to change custody, a new phenomenon that has arisen must necessitate it. More importantly, best interests of child must necessitate it. This is because main criterion for such a request is the best interests of the child. This approach is also compatible with the principle of priority of the best interests of the child.