A semiconductor device capable of detecting a micro-short circuit of a secondary battery is provided. The semiconductor device includes a first source follower, a second source follower, a transistor, a capacitor, and a comparator. A negative electrode potential and a positive electrode potential of the secondary battery are supplied to the semiconductor device, a first potential is input to the first source follower, and a second potential is input to the second source follower. A signal for controlling the conduction state of the transistor is input to a gate of the transistor, and an output potential of the first source follower related to the potential between the positive electrode and the negative electrode of the secondary battery is sampled. The comparator compares the sampled potential with an output potential of the second source follower, whereby the semiconductor device can deal with a secondary battery in which the potential between the positive electrode and the negative electrode is changed by charge and discharge.