Beneš studied Bohemistics and Germanistics at the Charles University in Prague, ending in 1930. Later, he worked on several places as a teacher in schools providing secondary education. After World War II he briefly worked at the Ministry of Education, then returned to the teaching. From the beginning of the 1960s he lectured at pedagogic institutes in Liberec and Ústí nad Labem.
Since 1933 he published articles about Czech surnames in specialised journals (as Naše řeč or Zpravodaj místopisné komise ČSAV, ZMK). In 1962 he published book "About Czech Surnames". His daughter, Dobrava Moldanová, collected many of his articles into book "Our Surnames" (1983). Posthumously "German Surnames of Czechs" was published in 1998, with Marie Nováková as an editor.