Since adjudication is one of the most essential and important subjects in the religious jurisprudence and law, the qualification of the judge is very important and so Islam underlines the competence and jurisdiction of the judges. This issue was negotiated from the time of Sheikh Tousi but in the last couple of century some open handed jurists that practically have tried to end the hostility have studied different sides of this subject more considerably. One of the conditions for the qualification of judge especially in religious jurisprudence is Ijtihad (divine law on matters of theology and law). The most famous jurists believe that Ijtihad is necessary in adjudication. They have indicated the narrative and rational reasoning about Ijtihad. The author of Javaher believes that only the Mojtahids who have all conditions are allowed to be a judge. On the contrary, some jurists, mostly the modern ones, believe that Ijtihad is not a necessary condition in adjudication and they talked in considering the lack of reasons that know Ijtihad a condition and the other persons who arenât Mojtahid can also be a judge. This article explains the forgoing aspects and then with the study and research about the theoretical principles of the common Ijtihad of judge, according to reliable documents, proves that Ijtihad for judges is not necessary.