NOVELTY - An adhesive (A1) for fuel cells used in producing a membrane-electrode assembly of a fuel cell, comprises: an olefinic poly(fluoroalkoxy)silane base compound (I); a polysiloxane cross-linking agent (II); an adhesion promoting agent; and a reaction catalyst. The ratio of moles of silicon-hydrogen groups contained in the cross-linking agent relative to moles of alkenyl groups contained in the base compound (moles of Si-H group/moles of alkenyl group) is 1-5.    USE - As an adhesive for producing a membrane-electrode assembly of a fuel cell (claimed) for solid polymer fuel cells useful for electric power generation.    ADVANTAGE - The adhesive provides a fuel cell with high bond durability between the polymer electrolyte membrane and the gas diffusion layer; and the adhesive layer requires less amount of heat for curing, thereby lowering the effects on the solid polymer electrolyte membrane.    DETAILED DESCRIPTION - An adhesive (A1) for fuel cells used in producing a membrane-electrode assembly of a fuel cell, comprises: an olefinic poly(fluoroalkoxy)silane base compound of formula H2C=CH-Si(CH3)2-(CF(CF3)-CF2O)n-Si(CH3)2-CH=CH2 (I); a polysiloxane cross-linking agent of formula H-Si(CH3)2-O-(Si(CH3)2-O)x-(SiH(CH3)-O)y-Si(CH3)2-H (II); an adhesion promoting agent; and a reaction catalyst. The ratio of moles of Si-H groups contained in the cross-linking agent relative to moles of alkenyl groups contained in the base compound (moles of Si-H group/moles of alkenyl group) is 1-5.    n=20-900.    Provided that the sum x+y is 10-900. An INDEPENDENT CLAIM is included for a membrane-electrode assembly for a solid-polymer fuel cell, comprising: a solid polymer electrolyte membrane; a catalyst layer provided on at least one surface of the solid polymer electrolyte membrane; a gas diffusion layer provided on the catalyst layer; and an adhesive layer provided at a periphery of the catalyst layer, and joining the solid polymer electrolyte membrane and the gas diffusion layer, where the adhesive layer contains the adhesive (A1) for fuel cells.