NOVELTY - The analyzer has a charging/discharging controller (11) for controlling charging/discharging of a secondary battery (1). A color imaging apparatus (20) projects illumination light through a transparent window (19) toward the battery positioned in a cell (10) for observation and images a color image of an active material layer to output time sequential color image data. A signal processing apparatus (12) is provided with an output unit that outputs the color image data of moving image format or two-dimensional color image data relevant to elapsed time of charging/discharging as analytical data.    USE - Analyzer for analyzing state change in charging/discharging of a secondary battery i.e. lithium ion secondary battery, that is utilized in a power supply device for an electric vehicle and a portable terminal. Can also be used for analyzing state change in charging/discharging of a sodium ion secondary battery and a magnesium ion secondary battery.    ADVANTAGE - The signal processing apparatus is provided with the output unit that outputs the color image data of moving image format or two-dimensional color image data relevant to elapsed time of charging/discharging as analytical data, so that local state change of internal structure of the secondary battery can be grasped by color change of the active material/shape and size change from outside, thus ascertaining distribution state of lithium of a positive electrode active material and distribution state of lithium in a negative electrode active material layer, and hence enabling capacity enlargement and high-speed charging/discharging of the battery to improve performance.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for analyzing state change in charging/discharging of a secondary battery.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic block diagram of an analyzer.'(Drawing includes non-English language text)'    Secondary battery (1)    Cell (10)    Charging/discharging controller (11)    Signal processing apparatus (12)    Transparent window (19)    Color imaging apparatus (20)    Monitor (22)