Human being is a unique creation that gifted with sense of knowledge and unlimited ideas about life, which, in this globalization era become one of the resources that came from human’s thoughts and it is called Intellectual Property Right. Trademark, as one of the intellectual property, has an important role for goods and services enhacement. Trademark is a sign that indicates the origin of goods or company’s services. Trademark is one of the intellectual property that needs to be protected by the law to prevent any fraudulent business behavior. Trademark is an important part in a business. Trademark is an indication of origin of the goods and services produced by company. It is also become the company’s priceless asset, especially the well-known trademark. Because of the important role that trademark has in the business, we often find trademarks specifically the wellknown ones, duplicated and sold by shady producer to take advantage from it. They take advantageof the well-known trademark for themselves without knowing that they have violated the owner rights. To protect it, the trademark needs to be registered at the Director General of the Intellectual Property Right. Relating to the registration of a trademark, according to Article 4 Law No. 15/2001, the trademark must be registered by the principle of good faith. If the trademark registration is done on the basis of bad faith, the trademark should be cancelled. On the legal decision of Medan District Courts’ Verdict No 03/PDT.SUSMEREK/ 2015/PN.Niaga Medan, the Panel of Judges state that the trademark “REZEKI” owned by the defendant are cancelled because of bad faith. The judge states that there are 3 causes of why the defendant’s trademark are cancelled because of bad faith and plaintiff as the valid owner of trademark “REZEKI”.