This research aims to analyze the inconsistency of annulment of an arbitration award in Supreme Court decision No. 26/Arb.G-Btl/2014. The methodology used in this research is normative legal research with statute legal approach and case approach. The results of research show the inconsistency of annulment of arbitration award in the Supreme Court decision No. 26/Arb. GBtl/ 2014 that is annulment of arbitration award of BANI No. 442/I/ARB-BANI/2012 for reason out of content of article 70 of Law No. 30 of 1999. That reasons are the application for annulling the arbitration award that didn’t attach the proving document that mention in the general elucidation of arbitration law and the jurisprudence of Supreme Court Decision No. 03/Arb.Btl/2005 which stated that the provision of article 70 of law No.30/1999 on Arbitration and ADR is not limitative and imperative, but it can be added and improved with the reasons out of content of article 70 as long as it is relevant reason. The recommendation is that there should be an additional point of article which provides guidance of using the reason out of content of article 70 of Law No. 30 of 1999 in the annulment of the arbitration award.