Business compition is competition among business actors in conducting activities for production and/or marketing. In terms to create fair business competition, the Indonesia goverment enacted Law Number 5 of 1999 Concerning The Prohibition of Monopolistic Practices and Unfair Business Competition that regulate business competition activities of business actor. Although there is a regulatory that regulates the business competition activities of business actor, there are still business actors that violate The Law Number 5 of 1999. One of the actions frequently committed by the business actor is Tender Conspiracy. As happened in the case of the Verdict of Commission For The Supervision Of Business Competition Number 13/KPPU-L/2015. In this thesis, the author will analyze how the regulatory of the tender conspiracy in Law Number 5 of 1999, and how The Commission For The Supervision Of Business Competition concludes that the tender conspiracy has been committed in this Verdict of Commission For The Supervision Of Business Competition Number 13/KPPU-L/2015. The author used normative research and 2 (two) kinds of approaches to analyze the Verdict of Commission For The Supervision Of Business Competition Number 13/KPPUL/ 2015, which are the law and case approaches. In Verdict of Commission For The Supervision Of Business Competition Number 13/KPPU-L/2015, there are 2 (two) business actors have committed to tender conspiracy. Not only 2 (two) bussines actors have committed to this tender conspiracy case but also the whole team of tender committes committed to this tender conspiracy case. The business actors and the whole team of tender committes of the project of development government office phase II of the public work services of south Nias Regency have committed to 3 (three) kinds of tender conspiracy. The 3 (three) kinds of tender conspiracy in this case are horizontal tender conspiracy, vertical tender conspiracy and horizontal and vertical tender conspiracy.