An operation plan creation device that is configured to create an operation plan for a plurality of parts to be mounted in a device includes a setting data acquisition unit configured to acquire setting data including information on a time of start of an operation of the part and a time of a scheduled performance of inspection of the part, and information on parts that are candidates for assignment to the device, for each device, an operation plan creation unit configured to create data of the operation plan including an operation period of the part from the time of the start of the operation to the time of the scheduled performance of inspection using the setting data, and an assignability determination unit configured to determine an assignability for the part.