A charging control method and a charging mechanism for a lithium ion secondary battery are provided that can determine the life of the lithium ion secondary battery with more accuracy and a simple configuration. A charging control method for a lithium ion secondary battery calculates an integrated value of the number of charged times. The method includes: adding a predetermined value to the integrated value of the number of charged times of the lithium ion secondary battery if both a residual voltage that is a voltage value of the lithium ion secondary battery before the beginning of charging and an elapsed time from the time of the previous charging of the lithium ion secondary battery are not less than predetermined values; and estimating the life of the lithium ion secondary battery based on the integrated value of the number of charged times.