The present invention relates to a remaining operating time measurement device and method of the battery. The remaining operating time of the battery measuring apparatus according to the invention and a discharge voltage measurement unit for measuring a discharge voltage of said battery; The number of reference discharge voltage curve stored in the discharge curve database; Of the plurality of the reference discharge voltage curve of the discharge voltage measured by the measuring unit extracts a close one to the discharge voltage and the discharge time of the battery, and the remaining to the end voltage preset in the reference discharge voltage curve on the extracted time and a first remaining operating time calculation section for calculating a first remaining operating time; Second remaining operating time calculation section for calculating a second group remaining operating time based on the remaining capacity of the battery is calculated from the measurement voltage range set based on the discharge voltage curve of the extract and; Characterized in that based on the average value of the first residual operating time and the second remaining time using a main control unit that calculates the final remaining use time of the battery. Accordingly, a number of reference discharge voltage curve based on the discharge state and close based on the discharge voltage curve of the current the battery using the first residual operating time and a second average value of the remaining operating time by calculating the final remaining use time of the battery, it is possible to predict the remaining usage time of the battery more accurate.