Ibnu Hadjar (born Haderi; 19 April 1920 – 22 March 1965) was an Indonesian Navy officer and later the leader of Darul Islam in South Kalimantan from 1950-1963.

Ibnu Hadjar was born on 19 April 1920 in Ambutun [id] with the original name Haderi.

In early 1950, Ibnu Hadjar joined United Indonesian State Army and was deployed to Pontianak for a short time.

[2] In early 1951, the chairman of Hulu Sungai Regional People's Representative, Zafry Zamzam [id], persuaded Ibnu Hadjar to surrender.

During the early four years (1950-1954), Ibnu Hadjar and his forces attacked Kandangan four times, and the government managed to repulse them.

Kartosoewirjo appointed Ibnu Hadjar as the Darul Islam Territorial Commandant of Kalimantan.

Looking at this situation, the police chief of South Kalimantan, Tengku Abdul Aziz, persuaded Hadjar and the rest of his forces to surrender with the promise of amnesty from the Jakarta government.