A battery diagnosis apparatus and a battery diagnosis method for accurately diagnosing a secondary battery are proposed. A pulse current generator, a voltage measuring instrument that measures a voltage response to application of a current pulse, a first data processing device that obtains a chronopotentiogram (CP) indicating a change in the voltage response over time and normalizes the CP, a database that saves normalized data, and a second data processing device that uses a correlation between the saved data and a battery state expressing factor prepared in advance to make a battery diagnosis are used. Desirably, the current pulse is a current in the same direction at the time of data obtainment and at the time of a diagnosis. Further, a noise filter for an input signal of the CP and resampling means for reducing the number of pieces of data input to the first data processing device are provided.