Family business is considered as one of the most popular form of business in Asia. According to Forbes (2017), Family businesses are on of the major pillars of Asian economies. Most of the businesses in Asia started out as a family business, which then developed and became larger business or corporations. Family businesses is unique because of the succession throughout generations and the strong participation of founder's family members in the business. The purpose of this research is to study the importance of involving founder's family members in the family business itself, and to understand the positive impact of family involvement on the operational management within P.T. Yuki Abadi Medan. The data used for this research are obtained through interval measurements in the form of questionnaires filled in by participants, who are supervisors and managers of the company. The data obtained from the questionnaires are analyzed using several statistical methods, such as validity test, reliability test, determination test, correlation test, and z test for hypothesis testing. The results obtained from the tests proved that the questionnaires are valid and reliable. The influence between the two variables is also proven to exist through the determination, correlation, and hypothesis testing. The null hypothesis is rejected; thus the alternate hypothesis is accepted. This research concludes that the involvement of family members in PT. Yuki Abadi generates positive impact on the company's performance. The involvement of family members is also significantly displayed in this company, as family members also take major parts in decision-making, projects and operational management in daily basis.