A capillary electrophoresis apparatus is disclosed that does not discharge and achieves both compactness and performance even with a part configuration having insufficient spatial distance or creeping distance. This capillary electrophoresis apparatus is provided with a resistance heater for heating capillaries, an electrode holder that holds capillary electrodes and is connected to a high-voltage unit, and a conductive member that at least partially comprises metal and has been grounded to a low potential. The electrode holder and conductive member are in contact with heat-dissipating rubber disposed there between that composes a structure comprising an insulation member. As a result of this configuration, discharge risk is reduced through the reduction of the potential of parts near the high-voltage unit and the slow reduction of the high potential of the high-voltage unit.