To provide an apparatus for transferring a reference liquid to a measuring instrument and a measuring instrument with such the apparatus capable of practicing at any time under almost same conditions and to provide the apparatus for transferring the reference liquid in order to decide a characteristic variable of a liquid sample.

The apparatus has an independent conduit element 6 and is able to insert an end of the element to a supply inlet 44 of a measuring instrument 36 and to insert the other end of the element to an ampule 52 containing a reference liquid 54. The apparatus has a holding device 4 holding the ampule 52 containing the reference liquid and the holding device is able to be fixed to the measuring instrument 36. By continuously supplying the reference liquid one by one, a high reproducibility is realized.