A transmitting device which transmits a plurality of streams is provided. The transmitting device comprises: a first multimedia data consisting of multimedia contents; a first synchronization information for synchronization of a second multimedia data consisting of multimedia contents; a first transmitting data including a first signaling data for the first multimedia data and a second signaling data for the second multimedia data, a data generating unit generating a second transmitting data including a second synchronization information for synchronization of the second multimedia data and the first multimedia data, a first transmitting unit transmitting the first transmitting data supplied from the data generating unit to a receiving device through a broadcasting network, and a second transmitting unit transmitting the second transmitting data supplied from the data generating unit to the receiving device through an IP network.