Langgaard married twice. His first wife was Henriette Catharine Frederikke Conradine Treschow (1818–1847), a daughter of Andreas Treschow (1794–1846) and Anne Marie Wendel (1797–1864). They were married on 17 December 1835 in Christiansborg Chapel. His second wife was Charlotte Sophie Magdalene Seydewitz (1826-1891), a daughter of Major Carl Christian S. (1777–1857) and Sophie Amalie Møller (1792–1863). They married on 20 March 1849 in the Garrison Church in Copenhagen. He was the father of pianist and composer Siegfried Langgaard and the grandfather of organist and composer Rued Langgaard.
