An operation support device is provided with: a similarity determination unit for determining the similarity between actual measured data and simulated data, said actual measured data being measured in an operation target after performing control on the operation target on the basis of, among a plurality of control candidates managed using a control candidate table, a control candidate corresponding to an event having occurred in the operation target, said simulated data being obtained by a simulation assuming the system state of the operation target after performing control on the operation target on the basis of system data indicating the state of the operation target before performing the control on the operation target; and a control candidate table update unit for updating the control candidate table in accordance with the determination result of the similarity determination unit.