At some date before 1474 he was appointed Inquisitor for the Tyrol, Salzburg, Bohemia and Moravia. His eloquence in the pulpit and tireless activity received recognition at Rome and he was the right-hand man of the Archbishop of Salzburg. By the time of the Bull Summis desiderantes of Pope Innocent VIII in 1484 he was already associated with Jacob Sprenger to make an inquisition for witches and sorcerers. In 1485 he drew up a treatise on witchcraft which was incorporated in the Malleus Maleficarum (literally "The Hammer of Witches").
Kramer failed in his attempt to obtain endorsement for this work from the top theologians of the Inquisition at the Faculty of Cologne, and they condemned the book as recommending unethical and illegal procedures, as well as being inconsistent with Catholic doctrines of demonology.
Major works 
- Malleus Maleficarum
- Several Discourses and Various Sermons upon the Most Holy Sacrament of the Eucharist, Nuremberg, 1496
- A Tract Confuting the Errors of Master Antonio degli Roselli, Venice, 1499
- The Shield of Defence of the Holy Roman Church Against the Picards and Waldenses, c. 1500
- "Institoris" is the Latin genitive case of "Institor" ("retailer"). It was a common practice in those times to take the genitive of the father's name for latinization, but this genitive was used as nominative in Latin texts ("Venerabilis & religiosus frater Henricus institoris"). In German texts this name was abridged to "Institor", according to the custom of omitting Latin endings in translations (cf. "Iuvenalis" - "Juvenal").
- Paul Hinschius. Das Kirchenrecht der Katholiken und Protestanten in Deutschland. Band VI. 1897. Reprint Guttentag, 1959.