A capillary array electrophoresis system by which measurement is conducted using a large number of capillaries. The electrophoresis system includes a plurality of capillary array sheets stacked one on top of another wherein end portions of the capillaries at a detection region are arranged two-dimensionally in such a manner as to elute two-dimensionally a sample from the distal end of each capillary. Excitation light is applied to the sample eluted into a buffer solution, and a two-dimensional fluorescent image is picked up by a detector.