In the recent Telecommunication has become a central part in human life which thigh competition among cellular operator. Especially, in June 2016 there is a case of business competition between Telkomsel and Indosat (the big Three Cellular operator in Indonesia). In Indonesia there are two Institutions that maintain business telecommunication and business competition namely Indonesian Telecommunication Regulatory Body (BRTI) has mandate by Law number 36 of 1999 and Business Competition Supervisory Commission (KPPU) by Law Number 5 of 1999. The research aims at know how the regulation regarding the dispute settlement on unfair business competition of cellular operator and to know the role of Indonesian Telecommunication Regulatory Body (BRTI) and Business Competition Supervisory Commission (KPPU) settle this case. The study is normative legal research with statute and case approach, by using juridical qualitative approach. The result of this research are, first to know the regulations regarding dispute settlement on unfair business competition of cellular operator. Second, to shows the dispute settlement on unfair business competition case of cellular operator by Indonesian Telecommunication Regulatory Body (BRTI) and Business Competition Supervisory Commission (KPPU) regarding with Law Number 36 of 1999 on Telecommunication and Law Number 5 of 1999 on the Prohibition of Monopolistic Practice and Unfair Business Competition.