Eiler Hagerup was born on 25 November 1685 in Kvernes in what is now Møre og Romsdal county, Norway.

His parents were the priest Hans Hansen Hagerup and his wife Ellen Eilersdatter Schøller.

at the end of his name means den eldre (English: the elder) to distinguish him from his younger nephew, Eiler Hagerup d.y.

In a letter to the priests in his diocese, he made strict demands: the catechism should be taught and the young people should learn to read with the book.

He made a great emphasis during his time as bishop of mission work among the Sami people in Northern Norway.