A membrane-electrode structure for a solid polymer fuel cell excellent in power generation performance and durability and a solid polymer fuel cell comprising the membrane-electrode structure are provided. In the membrane-electrode structure for a solid polymer fuel cell in which the polymer electrolyte membrane 2 is sandwiched between a pair of electrodes 1 containing a catalyst, the polymer electrolyte membrane 1 comprises a constituent unit (A) which has an ion conductive moiety consisting of a sulfonic acid group and is represented by the following general formula (I) and a constituent unit (B) consisting only of a non-ion conductive moiety which has a number average molecular weight in the range of 1,000 to 12,000 measured by gel permeation chromatography and is represented by the following general formula (II). The above-mentioned copolymer is a block copolymer in which the constituent unit (A) and the constituent unit (B) are covalently bonded. The solid polymer fuel cell comprises the above-mentioned membrane-electrode structure for a solid polymer fuel cell.

(wherein Y represents a divalent electron withdrawing group; Z represents a divalent electron donating group or a direct bond; Ar represents an aromatic group having a substitutent represented by -SO 3 H; m represents an integer of 0 to 10; n represents an integer of 0 to 10; and k represents an integer of 1 to 4.)

(wherein R 1 to R 8 , which may be the same or different, each represent at least one atom or group selected from the group consisting of a hydrogen atom, a fluorine atom, an alkyl group, a fluorine substituted alkyl group, an allyl group, an aryl group and a cyano group; W represents a divalent electron withdrawing group or a single bond; T represents a single bond or a divalent organic group and p represents 0 or a positive integer).