Provided is a low-cost battery pack capable of predicting a remaining battery life of a rechargeable battery with high accuracy. A remaining battery life prediction device includes: a voltage detection unit configured to measure a battery voltage and a battery temperature of the battery; a calculation unit configured to perform predictive calculation of a remaining battery life based on the battery voltage and the battery temperature; and a control unit configured to control operation of the remaining battery life prediction device and the calculation unit, the remaining battery life prediction device being configured to predict a remaining life of the battery with a calculation flow of for a predetermined time period, recursively calculating the remaining battery life based on the measured battery voltage and battery temperature and an internal impedance of the battery in a battery equivalent circuit.