Maimoon Palace or Maimun Palace () is an istana (royal palace) of the Sultanate of Deli and a well-known landmark in Medan, the capital city of Northern Sumatra, Indonesia. Today, it serves as a museum. The name is the Arabic word for "blessing".
Built by Sultan Ma'mun Al Rashid Perkasa Alamyah in the years 1887–1891, the palace was designed by the Dutch architect Theodoor van Erp and covers 2,772 m2 with a total of 30 rooms. The palace has become a popular tourist destination in the city, not solely because of its historical heritage status, but also because of its unique interior design of the palace, combining elements of Malay cultural heritage, Islamic and Indian architecture, with Spanish and Italian furniture and fittings.
It is the last surviving Melayu palace, the rest having been destroyed in the 1946 social revolution. Nearby British troops protected it.