Aleksander Järnefelt was born in Tohmajärvi, the son of crown overseer Gustav Adolf Järnefelt and Aurora Fredrika Molander. Aleksander married Elisabeth Clodt von Jürgensburg at December 22 in 1857 in Saint Petersburg. Their children were Kasper, Arvid, Erik, Ellida, Ellen, Armas, Aino, Hilja and Sigrid. Armas, Arvid and Eero were famous Finnish cultural figures. Aino Järnefelt was married to composer Jean Sibelius. Aleksander's work was first topography. At his command, in 1870s, many maps from the Uusimaa, Viipuri, Turku and Pori provinces were made.