A deterioration estimating apparatus estimates a deterioration state of an electric storage element when the electric storage element is used, a deterioration value indicating the deterioration state being in a proportional relationship with an nth root of an elapsed time (where n is a value larger than one), and the proportional relationship being changed in accordance with a deterioration condition. The apparatus includes a computing device accumulating change amounts of the deterioration value in a plurality of the deterioration conditions and calculating a deterioration value of the electric storage element when a predetermined time period elapses. The computing device predicts a period for which each of the deterioration conditions occurs before the elapse of the predetermined time period. The computing device calculates a change amount of the deterioration value in each of the deterioration conditions based on a deterioration characteristic indicating a relationship between the deterioration value and the elapsed time and the period of occurrence of each of the deterioration conditions, and adds the calculated change amounts sequentially by using the deterioration value provided before each addition as a reference to calculate each change amount of the deterioration value to be added.