PURPOSE: To obtain an electrophoretic device which can accurately recognize the migrating distance of protein even when no pigment is mixed with the protein.

CONSTITUTION: In an electrophoretic device which finds the distribution of fractionation protein 2 by making the protein to make electrophoretic migration on a carrier 1, a protein detector which specifically detects the protein by an optical method, etc., is provided so as to detect the electrophoretic migration of the protein. In addition, an electrophoretic power supply controller 8 which controls the electrophoretic current (voltage) or electrophoretic time of the electrophoresis processing means is also provided so as to control the migrating distance of the protein.