Disclosed are a signal transmitting method, a signal transmitting apparatus, and a system for transmitting and receiving a signal. The signal transmitting method comprises the steps of: discovering a companion device using a multicast mode; receiving and storing device type information from the discovered companion device; receiving an application uniform resource identifier (URI) and storing the application URI to correspond to the device type information; and identifying the device type information of the companion device selected by a user and transmitting to the selected companion device the application URI corresponding to the device type information.