A signal processing apparatus includes a connection section for being attachable to or detachable from an external device which reproduces content and attribute information of the content and a control section for controlling the external device which is mounted on the connection section. The control section acquires the attribute information from an external device, supplies a reproduction request for content to the external device, supplies content reproduced by the external device in response to the reproduction request to a reproduction device by streaming, and determines whether or not the content is completely reproduced using the acquired attribute information, and when it is determined that the reproduction of the content is completed, controlling the external device by stopping the reproduction of the content and notifying that the reproduction of the content is completed to the reproduction device.