A method of electrophoresis, an electrophoresis apparatus and a capillary array in which a fluorescently labelled sample is supplied into capillaries in a capillary array constituted by a plurality of capillaries and including a sample supply portion, an electrophoresis medium supply portion and a detection portion while controlling the temperature of the capillary array through gas circulation, the sample is caused to migrate and separated in the capillaries through electrophoresis, and at the region where the capillaries are contacted or come close each other a plurality of capillaries are contacted to a solid body so as to dissipate heat generated from the capillaries to the solid body.