Antanas Šopaga was born in Daukšiai village, Mosėdis rural district, Kretinga county. He finished a primary school in Daukšiai and a state gymnasium in Skuodas. In 1945-1946, he worked as a teacher at a school in his native Daukšiai. In 1947, he became a student of the Medical Faculty of Vilnius University. Soviet repression disrupted his studies: on 25 March 1949, Antanas Šopaga was deported to Irkutsk region. In 1958 he was released from exile and soon returned to Lithuania.