PURPOSE: To make it possible to accurately regulate the temperature of a capillary column to a predetermined operating temperature by dissipating or increasing the Joule heat generated by the current flowing through the column.

CONSTITUTION: The high performance capillary tube electrophoretic apparatus has a multilayer structure having a pair of capillary tube column placing members for placing a capillary tube column 12 as a part of the apparatus 10. When it is assembled in the final shape having the column 12, a detecting slot 42 is formed at auxiliary support plates 30 so that the plates 30 are respectively matched to the detecting slit 38 and detecting hole 40 of the capillary tube column placing detecting plates 28. The surfaces of the thermoelectric plates 32 opposed to the inner surfaces are disposed in the state in contact with the surface of the plates 30 opposed to the outer surfaces. Each plate 32 has at least one electroconductive circuit, i.e., a thermopile. The electrophoretic operation temperature of the column 12 is thermoelectrically regulated by controlling the movement of the thermal energy to the column 12 or from the column 12.