Procedural principles and rules of procedure along with formalities of procedure are contents of Civil procedure. Procedural principles which create the rules cause the basis of just proceeding. These rules provide preparations of observing principles. Neutrality of judge is one of the explained principles of public aspect of civil procedure and has a different meaning from principle of independence of judge, and causes some rules toward making the proceeding justly. The aim of this research is to get an understanding of neutrality of judge and monopolizing the rules resulted from it. The question is that what rules this principle causes in civil procedure. For answering this question, we should, at first, come to a proper understanding of the meaning and base of neutrality. In this regard, attempts have been done to restrain the rules issued from this principle through analyzing regulations and can be said as a result that neutrality of judge causes equal treatment with parties, public proceeding, justification of judgment and prevents judges from taking evidence. These rules guarantee the neutrality of judge during the trial and are course of the judge's actions during proceeding. Due to the necessity of efficiency of proceeding instead of fact-finding and termination of quarrel, judge actively cooperates with the parties with respect to a certain outline during the process of trial, but he is prevented from taking evidence to be neutral. In the same vein, legislatore has predicted requirements of equal treatment with parties in regulations. The basis of public proceeding is preservation of impatiality of judge by means of supervising the treatment and decisions of the judge. To cause the neutrality of judge be seen in his decision, his decision must be justified by means of documentation and reasoning, to be accepted as a judiciary decision of judge not a private decision.