An imaging support device used in a radiography apparatus including a radiation source and a radiation image detector that detects a radiation image of a subject on the basis of radiation emitted from the radiation source and transmitted through the subject, and includes an optical camera that outputs an optical image by optically imaging a region including an irradiation field of the radiation applied to the subject from the radiation source, and at least one processor, in which the processor executes a determination process of determining a possibility of reimaging in a case where radiography is performed on the basis of the optical image acquired by the optical camera before start of the radiography by using a trained model that has learned a relationship between the optical image captured during the radiography and a necessity of recapturing the radiation image that is captured during the radiography.