NOVELTY - An electrochemical reaction device comprises a positive electrode having a principal surface (S1) and a principal surface (S2) on the side opposite to the principal surface (S1), and a negative electrode having a principal surface (S'1) and a principal surface (S'2) on the side opposite to the principal surface (S'1). The principal surfaces (S1) and (S'1) of the positive and negative electrodes face one another, and the electrodes are positioned at a distance from one another so as to delimit a space between them. The space is filled with a conductive fluid and/or dielectric fluid.    USE - Electrochemical reaction device is used in chemical reaction for heat-treatment of cancer cells by generating heat using chemicals, and as secondary battery for wind power generation, photovoltaic power generation, buoyancy gravity electric power generation, and vehicle-mounted battery (all claimed).    ADVANTAGE - The economical electrochemical reaction device has excellent electric insulation property in electrolyte aqueous solution such as salt lake water and seawater, and provides battery having excellent capacitance. The liquid-repellent porous film which comprises the electrochemical reaction device has excellent alkali resistance, acid resistance, and chemical-resistance at high temperature, and mechanical strength and flexibility.    DETAILED DESCRIPTION - An electrochemical reaction device comprises a positive electrode having a principal surface (S1) and a principal surface (S2) on the side opposite to the principal surface (S1), and a negative electrode having a principal surface (S'1) and a principal surface (S'2) on the side opposite to the principal surface (S'1). The principal surfaces (S1) and (S'1) of the positive and negative electrodes face one another, and the electrodes are positioned at a distance from one another so as to delimit a space between them. The space is filled with a conductive fluid and/or dielectric fluid. An isolation tool (T1) for isolating the positive electrode from the fluid is positioned on the surface (S1) of the positive electrode, and an isolation tool (T2) for isolating the negative electrode from the fluid is positioned on the surface (S'1) of the negative electrode. The isolation tool (T1) includes a liquid-repellent porous film (11) having several small holes, and the isolation tool (T2) includes a liquid-repellent porous film (F2) having several small holes. The device further comprises a pressure-imparting instrument for pressurizing the fluid and filling the holes of the liquid-repellent porous films (F1) and (F2) with the fluid, by which the electrochemical reaction in which the positive electrode and the negative electrode are concerned is made to occur. An INDEPENDENT CLAIM is included for chemical reaction method.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of pressure switch.    Airtight container (1)    Negative electrode chamber (3)    Positive electrode chamber (4)    Liquid repellent porous film (11)    Weight (104)