The main purpose of this dissertation is to study and evaluate the historical background and the theological significance of Joint Declaration of Justification, which was issued twice by the Roman Catholic and the Protestant, in the view of the Ecumenical Movements. Farther more, with recognizing again the importance of Justification and without missing the identity of the Church, this dissertation will consider about the historical background and the theological significance, make a reconciliation and a bigger harmony of the Church and find the theological significance through the positive and negative estimation of it.Even though justification is one of the theological theories, actually, it seems to be the most essential and important theory. As we all know, because of His self-suffering and self-lowering for human beings who live without God, He makes them to be righteous. And through the justification God and human beings can make a harmony. Also it is the start and fact of God's salvation. The words mentioned above are not only the basic theory of the Christianity but also the most essential and important theory.This dissertation proves the meanings by researching the bible and the biblical documents. And this article studies the view of the Ecumenical Movements, analyzes and evaluates the significance of Joint Declaration of Justification by comparing former study-methods.This dissertation contains the following contents along the order of index. The first section contains introduction, the purpose and the importance of the study and the method and the limit of this article are mentioned. It includes also the historical basis and the recent trend of the justification study. In the second section, the origin of justification is considered in the bible. And then the justification by Jesus and the one by Paul are treated too. The third section cares about comparing the justification of Martin Luther and Roman Catholic and the one of the reformation by looking at the justification of Catholic, Luther, Calvin and Wesley in the view of God's Grace and man's responsibility. The fourth section is about considering the history and the theological significance of Ecumenical Movements. In the fifth section there is an analysis of the historical background and the theological inter-understanding of Joint Declaration of Justification and the significance of Joint Declaration of Justification about a justification doctrine. The sixth section shows what the contribution, the limit and the theological significance of Joint Declaration of Justification are. As the part of conclusion the seventh section indicates the summary of this article's purpose and its developing direction and achieving.Joint Declaration of Justification has an agreement according to the following view. First of all the justification is not by the man's merits but only by the almighty God's grace who is the Holy Trinity. Second, changing a sinner into the righteous man has no connection with keeping the laws well but only by having the faith about good-news can make it possible.But Joint Declaration of Justification has some different positions in following view. First, two church has the difference of the view about the justification's importance. Luther's church understands it as the only standard to judge every church and doctrine. However, Catholic church does it as one of many common standards. The second difference is about man's cooperation in justification. According to Luther church, even if it is granted to think of justification without man's cooperation, for the Roman Catholic church it is emphasized to do something for justification. Thirdly these two churches disagree about the sin which is made after the justification. Luther's insists that even the man who was made righteous by God recognizes the fact that his sin still remains with him when he watches himself in the view of the laws. On the other hand, Catholic church supports that the Grace of Jesus Christ which is given when the man was baptized removes his sin at all in the meaning of the essential basis. For the last they don't have the same opinion about the function of the laws, emphasizing the justification which does not have any connection with keeping the laws. In Luther's justification the laws' function is to reveal man's sin, but in Catholic's justification it is the duty that every man with justification has to serve.Like what was written above, all though their concepts of Joint Declaration of Justification is combined with the doctrine which means that the only God's grace of Trinity and man's faith about it can make the man righteous and is not combined with some issues which are like man's cooperation for justification and the sin after it.With having the evaluation of Joint Declaration of Justification, firstly, it is possible that it will bring not less effect to Ecumenical movement. The matter of justification is the main subject and theological element that could make Protestation and Catholic be separated. But it is true that the believer's justification only can be totally made by God's grace. All church agree with this fact and this theological position. So, it is possible to put a touchstone on this agreement. Secondly, unlike the fact that they have same opinion about the part of God's authority, there are still some disagreements about God and man's cooperation and the sin after the justification. Even though there is an obvious difference between Joint Declaration Protestation and Catholic churches, the fact that they made a conference that the theological doctrine difference is not a good reason for judging seems to be the important contribution for Ecumenical movement. Thirdly, however, these following things are not acceptable which are like Catholic understanding that justification is started by righteous grace and is being made righteous, through the holy spirit and the accommodation of His good-news, from the m