An imaging element incorporates a memory and a processor. The memory stores image data obtained by imaging a subject at a first frame rate. The processor is configured to derive a degree of difference between first image data obtained as the image data by performing imaging and second image data that is obtained as the image data earlier than the first image data and stored in the storage portion, and perform processing of deciding at least one of the first image data or the second image data as the output image data in a case where the derived degree of difference is greater than or equal to a threshold value. The processor is configured to output the decided output image data at a second frame rate.