Sei Mangkei Special Economic Zone or abbreviated as Sei Mangkei KEK, is a Special Economic Zone (SEZ) located in Bosar Maligas district, Simalungun Regency, North Sumatra, Indonesia. This SEZ has been established through Government Regulation No. 29 of 2012 on 27 February 2012. The development of SEZ Sei Mangkei is being focused mainly on Palm Oil and Rubber Processing Industry. SEZ Sei Mangkei was inaugurated by President Joko Widodo on January 27, 2015.