The contradictoriness is one of the fundamental principles in any proceedings. However، the concept of this principle in the criminal proceedings which has a fundamental difference with civil procedure especially because of existence of the preliminary investigation and the possibility of taking decisions without listening to statements and reasons of criminal claim parties، also the limits of implementation of this principle are not clear. So it is necessary to considering how to apply this principle، particularly in relation to the Criminal Procedure Act 1392، which seeks to further the adversarial criminal process such as a civil proceeding. contradictoriness in criminal procedure means that no decision against one of the public claim in any stages of the proceedings (prosecution، investigation and trial) should be made just after hearing testimony and considering evidences of public claim parties (accused and prosecutor). This principle is not explicitly mentioned by Criminal Procedure Act 1392 but the contradictoriness implicitly is accepted and the most important examples of implementation of this principle in this Act such as adversarial processing in the preliminary investigation stage in forgivable crimes and in the trial stage in the court، accessing to lawyer، prohibition of obtaining any defense bill، new document and evidence pursuant of announcement of termination of proceedings has been mentioned. However with regards to the unequal status of public claim’ s parties and international documents emphasis on improving accused's status through using human rights instructions including applying of the principle of contradictoriness in the criminal procedure so here we will mention examples in the Criminal Procedure Act 2013 in violation of contradictoriness against accused.