An analyzing apparatus according to an embodiment includes processing circuitry. The processing circuitry acquires a plurality of time-series medical images. The processing circuitry calculates, for each of image pairs each formed of two medical images included in the medical images, a first index value indicating similarity between image signals in the two medical images. The processing circuitry also calculates, on the basis of a plurality of the first index values calculated for the respective image pairs, a second index value corresponding to a statistical value in a time direction of the first index values.