To provide a polymer-electrolyte battery that is excellent in safety and also in load characteristics.

This polymer-electrolyte battery comprises a positive electrode capable of storing and releasing lithium ions, a negative electrode capable of storing and releasing, or precipitating/dissolving lithium ions, and a porous separator sheet. The battery has a polymer electrolyte between the porous separator sheet and the positive electrode, or between the porous separator sheet and the negative electrode. The battery is structured so that the liquid- retaining ability of a gel layer constituting the polymer electrolyte may be greater than the liquid-retaining ability of the laminate of the porous separator sheet and the gel layer as a whole.