Abstract: An exchanging device is for exchangeably holding a sensor, probe element or tool on a machine or on a machine part or a rotation-pivot unit on a machine or a machine part, preferably, a coordinate measuring apparatus. The exchanging device includes a take-up holder having a first bearing part and a counter piece (22) having a second bearing part corresponding to the first bearing part. A releasable clamping unit (42), for example, a magnetic clamping unit, is provided with which a clamping force is generated between the first and second bearing parts when the counter piece is accommodated on the take-up holder. A locking device having a first locking element (29) is provided on the take-up holder and a counter piece corresponding to the locking element (29) of the take-up holder is provided on the counter piece (22), for example, in the form of a slider (30). With the locking device, the counter piece can be mechanically coupled to the take-up holder in the state when it is taken up by the take-up holder.