A data transfer device that includes a data acquisition means for acquiring data from another device and storing the data in a buffer and a communication means for transmitting the data stored in the buffer to a server connected to the data transfer device via a predetermined network, the data transfer device comprising: a line state acquisition means for acquiring line state data relating to a state of a line; a line state storage means for accumulating and storing the line state data acquired by the line state acquisition means; a transmission data amount determination means for determining an amount of transmittable data as the amount of data transmittable by one connection with the server, based on the line state data stored in the line state storage means; and a transmission schedule generating means for generating a transmission schedule for data transmission to the server based on a total amount of data stored in the buffer and the amount of transmittable data, wherein the communication means transmits the data stored in the buffer according to the transmission schedule, when the total amount of the data stored in the buffer is larger than the amount of transmittable data, the transmission schedule generating means includes information for enabling the communication means to transmit the data stored in the buffer by dividing the data according to a plurality of connections, in the transmission schedule, and the transmission schedule generating means determines a time interval when transmitting the data divided according to the plurality of connections based on (i) a value obtained by dividing the total amount of the data stored in the buffer by the amount of transmittable data, and (ii) an allowed transmission time that the transmission schedule generating means determines based on a current time and a time when the data acquisition means acquires data next. a line state acquisition means for acquiring line state data relating to a state of a line; a line state storage means for accumulating and storing the line state data acquired by the line state acquisition means; a transmission data amount determination means for determining an amount of transmittable data as the amount of data transmittable by one connection with the server, based on the line state data stored in the line state storage means; and a transmission schedule generating means for generating a transmission schedule for data transmission to the server based on a total amount of data stored in the buffer and the amount of transmittable data, wherein the communication means transmits the data stored in the buffer according to the transmission schedule, when the total amount of the data stored in the buffer is larger than the amount of transmittable data, the transmission schedule generating means includes information for enabling the communication means to transmit the data stored in the buffer by dividing the data according to a plurality of connections, in the transmission schedule, and the transmission schedule generating means determines a time interval when transmitting the data divided according to the plurality of connections based on (i) a value obtained by dividing the total amount of the data stored in the buffer by the amount of transmittable data, and (ii) an allowed transmission time that the transmission schedule generating means determines based on a current time and a time when the data acquisition means acquires data next.