The present invention relates to a power storage system including a negative electrode which has a crystalline silicon film provided as a negative electrode active material on the surface of a current collector and contains a conductive oxide in a surface layer section of the crystalline silicon film. Alternatively, the present invention relates to a method for manufacturing a power storage system, which includes the step of forming an amorphous silicon film on a current collector, adding a catalytic element for promoting crystallization of the amorphous silicon, onto a surface of the amorphous silicon film, heating the amorphous silicon film with the catalytic element added to crystallize the amorphous silicon film and thereby form a crystalline silicon film, and using the crystalline silicon film as a negative electrode active material layer.