[Problem] To provide a laminated ion exchange membrane for water electrolysis that has high gas barrier properties and low membrane resistance. Also to provide a method for continuously manufacturing a thick laminated ion exchange membrane with high gas barrier properties, wherein the method limits increases in membrane resistance and peeling does not occur even in cases of high water content such as in a liquid phase. [Solution] A laminated ion exchange membrane obtained by filling an ion exchange resin in the voids of a laminated porous substrate film in which multiple sheets of a porous substrate film with 30-50% porosity and mean pore diameter of 0.01 µm to less than 0.1 µm are laminated, wherein the total thickness of the porous substrate film is 50-200 µm, and the difference in porosity of adjacent porous substrate films is 10% or less.
