Disclosed is a relay for a simultaneous data transmission using multiple networks including: a connection control unit configured to control a terminal equipment to connect to multiple networks, when sensing entrance of the terminal equipment currently connected with a macro base station of the mobile communication network into simultaneous transmission service coverage serviced by the multiple networks, at least one of the multiple networks including at least one micro base station; and a relay processing unit configured to partition data transmitted or received to/from the terminal equipment into partial data corresponding to each of the multiple networks, and transmit and/or receive the partitioned partial data through each of the multiple networks.