An analyzing instrument (2) according to the present invention includes a capillary (6), a sample liquid inlet (42), and a liquid introduction controller for a controlled pattern of introduction of the sample liquid into the capillary. The capillary (6) preferably includes a common passage (60) and a plurality of individual passages (61-63) connecting to the common passage. In this arrangement, the liquid introduction controller selects for each of the individual passages (61-63) whether or not the sample liquid is introduced therein. The liquid introduction controller includes, for example, one or more through-holes (51-53) each communicating with e.g. the individual passages (61-63). The liquid introduction controller preferably selects for each of the individual passages (61-63) whether or not the sample liquid is introduced therein, by a selection whether or not the corresponding one of the through-holes (61-63) is opened or closed.
