An electrolyte membrane for a solid polymer fuel cell according to the present invention is a laminated body of (1) a first layer 11 comprising an ion exchange resin and (2) a second layer 12 comprising a porous body and an ion exchange resin filled into the fine pores of the porous body and is characterized in that an ion exchange capacity of the ion exchange resin for the second layer 12 is higher than an ion exchange capacity of the ion exchange resin for the first layer 11. Consequently, both of output performance and durability can be achieved simultaneously at a high level.