A programmable logic device that includes a storage device having smaller area and lower power consumption is provided. The programmable logic device includes a logic block including a storage device. The storage device includes a plurality of groups each including at least a first switch, a transistor that is turned on or off in accordance with a signal including configuration data input to a gate of the transistor through the first switch, and a second switch controlling the electrical connection between a first wiring and a second wiring together with the transistor when the second switch is turned on or off in accordance with the potential of the first wiring. In the logic block, the relationship between the logic level of a signal input and the logic level of a signal output is determined in accordance with the potential of the second wiring.