An anchor (1) comprising an anchor tube (2) and an inner tube (3) arranged in the anchor tube (2) for receiving a dispensable chemical mass (4). The anchor tube (2) has a first end (5) with a drilling head (6) and a second trailing end (7), at which a drilling machine can be coupled for rotary driving of the anchor (1). The anchor (1) further has a centering assembly with a first centering element (11) and a second centering element (21), which hold the inner tube (3) both radially and axially aligned in the anchor tube (2) by means of radial stop surfaces (17, 18) and axial stop surfaces (16, 26).