To provide a secondary battery and its manufacturing method realizing high discharge rate characteristics.

This battery 1 contains a stacked body of a positive electrode 2 and a negative electrode 4 both formed by binding an active material, current collectors 5, 6 for the positive electrode 2 and the negative electrode 4 respectively, and an electrolyte 3, and a sealing material 9 for sealing the stacked body, and the porosity of at least one of the positive electrode 2 and the negative electrode 4 is increased by removing part of the organic binder for binding the active material. The removing of the organic binder is conducted by treating the positive electrode 2 or the negative electrode 3 with a liquid capable of dissolving the organic binder contained in the positive electrode or the negative electrode.