To provide an operation leaning method of a hot water storage type electric water heater capable of predicting a thermal load by precisely integrating past thermal load results in correspondence with a life pattern of a user.

Integrated thermal load results for each of time zones are stored in a thermal load storage means 44 every time zone of every day of the week. A week integrating means 45 integrates the thermal load in the time zone of every day of the week every time zone of every day, and outputs it as a week integrated thermal load of the time zone. A leaning update time determination means 46 extracts the time zone when the week integrated thermal load is minimum in each of the time zones, and the prescribed time in the extracted time zone is made the leaning update time. An operation plan determination means 47 integrates the past thermal load results of one day by making the learning update time as a starting point for calculation, and the operation plan is made or updated based on the integrated value of the one day.