A method for transmitting broadcast and data streams in an HFC-based cable network includes a first transmission step of a broadcast transmission apparatus sending broadcast and data service streams in an IP-based stream or RF signal form through an optical section up to a cell node that is a contact point between the optical section and a cable section of a cable network and a second transmission step of the cell node converting the broadcast and data service streams into one of RF signal, IP-based stream, and RF/IP convergence service stream forms depending on a service type of a subscriber terminal and sending the converted broadcast and data service streams to the subscriber terminal through the cable section.