Abstract: The apparatus uses a holding device (2) which has a support ring (3) and a fixed ring (4). A cell substrate (1) is held between support ring (3) and fixed ring (4). The fixed ring (4) has a thickness less than the cylindrical height (3') of the support ring (3) so that only the support ring abuts against the surface of the culture vessel. Since fixing ring (4) does not abut against a surface, there is no pressure on the cell substrate (1). The holding device (2) is held inside the apparatus with space on both the apical and basal sides. Inflow ports (13) and outflow ports (14) are provided for both apical space and basal space to allow for introduction of cell treatment medium.