It is provided a management computer which refers to switching level information including switching patterns to be used at a time of switching the first task to the second application server; sets a level of a degree of safety for each of the switching patterns; refers to a stop time for each first task which is allowed upon switching the first task to the second application server; selects one of the switching patterns having a switching time that is shorter than the stop time of the task requirement information which is set to the first task and having the level of the degree of safety that is highest among the switching patterns of the switching level information; stops the second task of the second application server by the selected one of the switching patterns; and then controls the second application server to provide the first task.