1. A method for managing a plurality of target devices, the plurality of target devices being arranged in a same household, the method comprising: receiving, by an input associated with a first target device among the plurality of target devices, a voice command that includes first voice information, the voice command indicating an operation instruction for one of the plurality of target devices, the first voice information including identification information that identifies the first target device; specifying the first target device by referencing a database in which the identification information and a device ID of the first target device are associated; recognizing the operation instruction from the voice command; determining whether or not the voice command includes second voice information that identifies a second target device among the plurality of target devices as an operation object for the operation instruction; when the second voice information is not included in the voice command, causing the first target device to execute the operation instruction; and when the second voice information is included in the voice command, transmitting a control command to the second target device identified as the operation object for causing the second target device to execute the operation instruction.