A programmable logic device that verifies whether configuration data is stored correctly is provided. The programmable logic device includes a configuration memory storing configuration data input to a first wiring and a switch controlling conduction or non-conduction between a second wiring and a third wiring in accordance with the configuration data stored in the configuration memory. Further, whether the configuration data input to the first wiring agrees with configuration data actually stored in the configuration memory is verified by comparing the potential of the second wiring with the configuration data input to the first wiring.