Provided is a technology that can improve a cycle property without lowering a volume energy density. The present technology provides a method for evaluating a secondary battery, including conducting at least: a determination step of determining a degree of diffusion defect of an ion that performs electric conduction; an evaluation step of evaluating a state of the secondary battery on the basis the result of the determination in the determination step; and a control step of controlling states of current application and voltage application on the secondary battery during charging or during discharging of the secondary battery on the basis of the result of the evaluation in the evaluation step.