A software rewriting device, configured to rewrite software of a moving body, includes: a required time acquisition unit configured to acquire information regarding a required time for rewriting the software; a scheduled stop time acquisition unit configured to acquire information regarding a scheduled stop time at a predetermined position of the moving body; and a rewriting processing unit configured to execute a rewriting process of rewriting the software. When the required time is shorter than the scheduled stop time based on the information regarding the required time and the information regarding the scheduled stop time, the rewriting processing unit executes the rewriting process at the predetermined position, and when the required time is longer than the scheduled stop time based on the information regarding the required time and the information regarding the scheduled stop time, the rewriting processing unit does not execute the rewriting process at the predetermined position.