He attended the Faculty of Philosophy of Comenius University in Bratislava.
After completing his studies in Slovakia he started working as a journalist, editor of the Nový Život magazine, editor-in-chief of the children‘s magazine Pionieri. From 1988 to1993 he was the director of the Obzor –Tvorba publishing house.
In 1993 he moved with his family to Slovakia where he worked as a published until 2013 when he retired.
Demák is the author of following poetry collections: From Open Palm (1974), Zodiac (together with Víťazoslav Hronec), Between two Fires (1977), and the poetry selection Reconstructing Elsinore (2008).
He has translated about twenty books from the Serbian, Croatian, Macedonian, Ruthenian and German language.
His books have been translated into the Serbian, German, Croatian, Rumanian and Macedonian language