Demak Great Mosque Museum, History museum at Demak Great Mosque, Indonesia.

The Demak Great Mosque Museum is a history museum housed within a historic mosque in Demak, Indonesia, containing artifacts, documents, and historical items. The collections illustrate Islamic development across Java over many centuries.

The museum opened in 2014, funded with Rp1.1 billion from the Demak regional budget and the Mosque Welfare Board (BKM) of the Great Mosque of Demak. It occupies a 16-square-metre plot inside the mosque complex and holds more than 60 objects linked to the mosque, including the Bledeg Door made by Ki Ageng Selo in 1466.

The museum keeps objects tied to the mosque's founders: a saka guru pillar attributed to Sunan Kalijaga, Sunan Bonang, Sunan Gunungjati and Sunan Ampel, plus a wooden tatal pillar by Sunan Kalijaga. Two large Ming-dynasty jars were a gift from Putri Campa in the 14th century. The Bledeg Door, carved by Ki Ageng Selo, carries the chronogram Nogo Mulat Saliro Wani, read as 1466 CE.

The museum sits inside the Masjid Agung Demak complex on Jl. Sultan Patah No. 57, off the town alun-alun, and opens Monday to Sunday during working hours. It occupies a 16-square-metre space, so the more than 60 objects are seen at close range; allow time to read the labels on the wooden inscriptions and the handwritten Qur'an.

The museum's best-known piece is the Pintu Bledeg, a teak door carved by Ki Ageng Selo in 1466 with vines, jars, a crown and an open-mouthed dragon showing sharp teeth. Its carvings form the chronogram Nogo Mulat Saliro Wani, giving the year 1388 Saka (1466 CE). Legend says the dragon head depicts the lightning Ki Ageng Selo caught.