Ever, one of superiorities of investigation of judgment Institution on Justice administration is speed and acceleration in investigation. Thus contrary to Courts of justice that the claims are not  bound to time and special term, in judgment, the parties with determining a given term in the contract, oblige the judge to investigate and pronounce in the mentioned term. In lease contract, by virtue of Article 468 of Civil law, if no determination of lease period , the contract is annulled.  But in arbitration, despite to arbitration contract, without deadline is  unimaginable (such as legal or contractual), but the legislator has taken hard less on this regard and firstly has empowered to the parties determine arbitration term and if no determination of the term in agreement letter, the legislator  as completion law , has entered to the field and has determined the contract for 3 months. Delegation to extend the arbitration in beginning of affairs to rule of intent of the parties is not faced with a difficult