An arrangement for mounting of a rotation element in a drilling machine comprising a body (1) and a rotation element (8) mounted by means of bearing surfaces (8a, 8b) rotatably in the body for rotation of a drill shank (9). The rotation element is rotated by a rotation machinery (10) in engagement with a gear ring (11) of the rotation provided in the rotation element between the bearing surfaces. In order to replace the rotation element without having to disassemble the body, the rotation element is mounted at both ends thereof in the radial direction in an integral body part (3), and the bearing surfaces and the gear ring are arranged in a stepped manner so that the rotation element is removable from the integral body part axially through one end (3c) thereof.