A load distribution device includes: a combining unit to create a plurality of combinations for cases where each of a plurality of execution object programs is assigned to any one of a plurality of control devices; an estimating unit to estimate an all programs' completion time, which is a delay time taken from delivery of the plurality of execution object programs until return of execution results of the plurality of execution object programs to a delivery source, for each of the plurality of combinations created; and a selecting unit to select one combination whose all programs' completion time is shorter than a reference time, from the plurality of combinations created.