In an apparatus for analyzing small number of samples, wasteful consumption of a polymer as a separation Medium is suppressed.The apparatus has a configuration provided with a plurality of capillary units each of which can be attached/detached to/from the apparatus, and performs analysis for capillaries after sealing of a polymer by attaching the capillaries by the number in accordance with the number of samples. Since analysis can be performed by using capillaries by the number identical with that of the samples to be analyzed, wasteful polymer is not used in the capillaries not used for the analysis. In addition, the polymer injection mechanism is unnecessary and the polymer is not necessary for maintenance and upon starting of analysis. An electrophoresis apparatus which is small in the size with no polymer injection mechanism, and with low running cost not wastefully consuming the polymer can be provided.