A transmission device according to an embodiment includes one or more processors. The processors divide a plurality of pieces of transmission data to be transmitted into first data and second data. The processors transmit the first data to a server device configured to distribute the transmission data to a reception device. The processors store the second data in storage. The processors receive, from the reception device or the server device, a request for transmission of the second data. The processors transmit the second data to the server device in accordance with the request for transmission.