A novel semiconductor device is provided. The semiconductor device includes a programmable logic device including a programmable logic element, a control circuit, and a detection circuit. The programmable logic device includes a plurality of contexts. The control circuit is configured to control selection of the contexts. The detection circuit is configured to output a signal corresponding to the amount of radiation. The control circuit is configured to switch between a first mode and a second mode in accordance with the signal corresponding to the amount of radiation. The first mode is a mode in which the programmable logic device performs processing by a multi-context method, and the second mode is a mode in which the programmable logic device performs processing using a majority signal of signals output from the logic element multiplexed by the plurality of contexts.