A memory element having a novel structure and a signal processing circuit including the memory element are provided. A first circuit, including a first transistor and a second transistor, and a second circuit, including a third transistor and a fourth transistor, are included. A first signal potential and a second signal potential, each corresponding to an input signal, are respectively input to a gate of the second transistor via the first transistor in an on state and to a gate of the fourth transistor via the third transistor in an on state. After that, the first transistor and the third transistor are turned off. The input signal is read out using both the states of the second transistor and the fourth transistor. A transistor including an oxide semiconductor in which a channel is formed can be used for the first transistor and the third transistor.