Since the enactment of Law Number 19 of 1992 on Trademarks that had been amended last with the enactment of Law Number 20 of 2016 on Trademarks, it applies the Constitutive System (First to File) which is a change from the old system of the Declarative System (First to Use). Therefore, the legal protection is determined by a registration. However, there are still many lawsuit cases of trademark cancellation. Based on the Constitutive System, the right is granted to the first registrant. Some cases are based on a lawsuit from a party who feels as the owner of the trademark, but registered by another party. The research study, titled Legal Protection of the Registered Trademark Owner in the Constitutive System (First to File) in Indonesia, based on the problem: the first problem is how is the form of legal protection of registered trademark owner in the Constitutive System in Indonesia?