Provided is an apparatus for detecting biopolymers (DNA) capable of total analysis including non-reacted samples without complicated operations such as washing. A DNA probe is fixed to one of electrodes and direct current voltage is placed between the electrodes, so that it becomes possible to separate complementary strand sample DNA and non-complementary strand sample DNA. By analyzing from a ratio in the whole reaction system, it is possible to obtain clearer results. Further, by using electrophoresis by gel together, it is possible to separate reacted samples and non-reacted samples to perform measurements therefor in the same reaction field.