An information transmission method performed by a first device, the method comprising: receiving (S302, S1102) a selection, performed by an external input device, of target information displayed on the first device; extracting the target information corresponding to the selection performed by the external input device; and transmitting, via a first wireless communication interface, the target information or metadata corresponding to the target information to the external input device, wherein the step of transmitting to the external input device comprises: detecting a size of the target information; receiving (S304, S1104, S1702) an information transmission request signal corresponding to the target information including information on the available storage capacity of the external device; if the size of the target information is less than or equal to an available storage capacity of the external input device, transmitting, via the first wireless communication interface, the target information to the external input device, and if the size of the target information is greater than the available storage capacity of the external input device, transmitting, via the first wireless communication interface, only the metadata corresponding to the target information to the external input device, wherein the metadata includes information for a second device to request and receive the target information from the first device, receiving, from the second device, if the second device stores the metadata, a request for the target information based on the metadata, and transmitting, via a second wireless communication interface, the target information to the second device. receiving (S302, S1102) a selection, performed by an external input device, of target information displayed on the first device; extracting the target information corresponding to the selection performed by the external input device; and transmitting, via a first wireless communication interface, the target information or metadata corresponding to the target information to the external input device, wherein the step of transmitting to the external input device comprises: detecting a size of the target information; receiving (S304, S1104, S1702) an information transmission request signal corresponding to the target information including information on the available storage capacity of the external device; if the size of the target information is less than or equal to an available storage capacity of the external input device, transmitting, via the first wireless communication interface, the target information to the external input device, and if the size of the target information is greater than the available storage capacity of the external input device, transmitting, via the first wireless communication interface, only the metadata corresponding to the target information to the external input device, wherein the metadata includes information for a second device to request and receive the target information from the first device, receiving, from the second device, if the second device stores the metadata, a request for the target information based on the metadata, and transmitting, via a second wireless communication interface, the target information to the second device. detecting a size of the target information; receiving (S304, S1104, S1702) an information transmission request signal corresponding to the target information including information on the available storage capacity of the external device; if the size of the target information is less than or equal to an available storage capacity of the external input device, transmitting, via the first wireless communication interface, the target information to the external input device, and if the size of the target information is greater than the available storage capacity of the external input device, transmitting, via the first wireless communication interface, only the metadata corresponding to the target information to the external input device, wherein the metadata includes information for a second device to request and receive the target information from the first device, receiving, from the second device, if the second device stores the metadata, a request for the target information based on the metadata, and transmitting, via a second wireless communication interface, the target information to the second device.