A bioassay plate is provided with a pair of opposing electrodes in a reaction region, and by imposing a predetermined electric field on the reaction region, the bioassay plate makes it possible to perform high-order structural adjustment, migration, immobilization and the like of a substance as desired. A first substrate (11) is provided with a detection well (X), which is in turn equipped at least with a reaction region (R) for providing a place of interaction between the substances and also with a first electrode (E11) arranged facing the reaction region (R). A second substrate (12) is provided at least with a second electrode (E12) which can impose an electric field on the reaction region (R) in association with the first electrode (E11). The present invention provides a bioassay plate (1) formed of these two substrates (11), (12) stacked together such that the first electrode (E11) and the second electrode (E12) are located opposite to each other, and also a production method of the plate (1).