Disclosed is a biodevice which has a porous membrane (8) and flow paths (10) and (12) formed therein. In a preferred embodiment, the flow path (10) and the flow path (12) are opposed to each other with the porous membrane (8) being interposed between them. The flow path (10) serves as a first reaction chamber through which a first solution is allowed to pass so as to be brought into contact with one of the surfaces of the porous membrane (8). The flow path (12) serves as a second reaction chamber through which a second solution is allowed to pass so as to be brought into contact with the other surface of the porous membrane (8). In the flow path (10), first cells are immobilized on the porous membrane (8). In the flow path (12), second cells are immobilized on the porous membrane (8).