Abstract: Method and apparatus of installation of a membrane to a finger type electrolytic cell are provided, which comprise covering the horizontal surfaces of a cathode not opposing an anode with a membrane installation frame having a collar, positioning the membrane substantially parallel to the vertical surfaces of the cathode, and installing and securing the membrane to the collar by clipping. Not only is operation efficiency for the membrane installation to the electrolytic cell markedly improved, but also, in the case of an ion exchange membrane, an alkali metal hydroxide liquor hardly containing an alkali metal chloride is produced. According to the invention, a conventional asbestos diaphragm finger type electrolytic cell is advantageously converted to an ion exchange membrane electrolytic cell.