The article is devoted to the biography of the Russian nobleman, Second Major of the Preobrazhensky Life Guards Regiment, Ivan Mikhailovich Oznobishin (circa 1713 — before 1775). He was the father of the translator Nikanor Ivanovich Oznobishin, the grandfather of the diarist Pyotr Nikanorovich Oznobishin, and the great-grandfather of the poet Dmitry Petrovich Oznobishin. Based on archival documents, his service career has been reconstructed, and the lands and estates he owned have been identified. Ivan Mikhailovich Oznobishin was born around 1713 into the noble family of Mikhail Andreevich Oznobishin (1681 — circa 1735) and his lawful wife Avdotya Ivanovna, née Borisova (?–1748). Ivan Mikhailovich began his service in 1729 in the Preobrazhensky Life Guards Regiment. In 1737, he was transferred to another regiment, but in 1740 he was returned to the Life Guards. In 1741, he was promoted to the rank of Ensign of the Guards. In 1742, he became Adjutant of the Regiment; in 1751, he received the rank of Captain-Lieutenant, and in 1754, that of Captain. In 1763, Ivan Mikhailovich Oznobishin retired with a promotion in rank (Second Major of the Life Guards). A fairly wealthy landowner, he settled in the village of Sumarokovo in the Moksha District of the Penza Governorate. He was married to Agnia Petrovna, née Akinfova (1713–?), and the couple had two sons — Nikanor (the elder) and Alexander (the younger) — and a daughter, Olga. Ivan Mikhailovich owned the villages of Sumarokovo (also known as Bogorodskoye) in the Penza District; Arkhangelskoye (also known as Vrazskoye, Vratskoye, Vrazhskoye, Chanbar, Mikhailovka) in the Penza District; Troitskoye (also known as Syuksyum) in the Karsun District; the villages of Teplovka and Oznobishino in the Saransk District; the village of Vnukovo in the Gorokhovets District; he also had a hereditary estate in the village of Borovitsy (Borovichi) in the Murom District. Thus, Ivan Mikhailovich owned between 519 and 900 serfs, which made him a wealthy landowner. He died before 1775.