Born 4 March 1915 in Skalica. After graduating from the gymnasium he enrolled in Comenius University, studying and philosophy (1938 - 1942) where he also obtained a doctorate in philosophy (1944). Between 1942 and 1943, he worked as an editor of Národné noviny in Martin. After the liberation in 1945, he joined the editorial board of the daily Pravda and in 1949 he switched to the Pravda publishing house.
In 1951 he became an editor of the Kultúrny život, then worked in the Slovenský spisovateľ publishing house (1953 - 1955). From 1955 he taught at the Pedagogical Institute in Bratislava and after its closure at Comenius University where he was appointed associate professor of literature in 1971. In 1967 - 1969 he was lector in at the University of Strassbourg. Bunčák died on the 5th January 2000 in Bratislava.