A management application generates task information including device IDs, the device IDs identifying devices to be subjected to processing according to the task information, generates a plurality of pieces of sub-task information with device IDs of one or more devices subjected to the processing and an agent ID of an agent corresponding to the one or more devices, instructs a plurality of agents to start a task, transmits the sub-task information to the agent corresponding to the agent ID, sets an execution result of a sub-task received from the agent to sub-task information corresponding to the sub-task, and sets, in response to the execution result having been set to all pieces of the sub-task information, an ending date to the task information.