Regen was born in the village of Lajše (now Slovenia). His mother encouraged his interest in insect sounds. His father lost a lot of money bring cloth into Slovenia and could not pay for Ivan to go to school. Ivan was given a scholarship so that he could go to school at the local seminary. He was able to save enough money go to study in Vienna. He studied natural history at the University of Vienna with teachers Grobben, Exner and Claus. He got his doctorate in 1897 and began to work as a school teacher in Vienna, and later in Hranice, Moravia. Exner helped him get a job back in Vienna. He worked in a secondary school there until his retirement in 1918.