A battery control circuit having a novel structure, a battery protection circuit having a novel structure, and a power storage device including the battery circuit are provided. A semiconductor device includes n cell balancing circuits that respectively correspond to one secondary battery and each include a transistor, a comparator circuit, and a capacitor. In each of the n cell balancing circuits, an inverting input terminal of the comparator circuit and one electrode of the capacitor are electrically connected to one of a source and a drain of the transistor. The semiconductor device has functions of supplying a ground potential to the other electrode of the capacitor; turning on the transistor; supplying a first potential to the one electrode of the capacitor; turning off the transistor; electrically connecting the other electrode of the capacitor and a negative electrode of the secondary battery corresponding to each cell balancing circuit; supplying a sum of the first potential and a potential of the negative electrode of the secondary battery corresponding to each cell balancing circuit, to the one electrode of the capacitor; and controlling charging of the secondary battery corresponding to each cell balancing circuit.