A data transmitting device comprising: a beam forming processing unit configured to perform beam forming processing with a terminal provided in a moving object; a beam angle detection unit configured to detect a beam angle based on a result of the beam forming processing; and a moving object position estimation unit configured to estimate a position of the moving object based on the beam angle and installation position information of the data transmitting device, wherein the data transmitting device determines whether the estimated position of the moving object is within a communication area of the data transmitting device, and wherein the data transmitting device transmits desired data to the moving object if it is determined to be within the communication area, wherein the data transmitting device fragments the desired data pursuant to an allowable transmission unit and transmits the fragmented data, wherein the moving object is a plurality of moving objects forming a prescribed group, wherein with respect to one of the plurality of moving objects forming the group, the data transmitting device determines whether it is possible to complete transmission of the data while the one of the plurality of moving objects is staying in the communication area based on the estimated position of the moving object and a size of the data, wherein the data transmitting device fragments the data if it is determined that it is not possible to complete the transmission of the data while the one of the plurality of moving objects is staying in the communication area, and wherein the data transmitting device transmits different fragments of the data to the one of the plurality of moving objects and other moving objects forming the group, respectively, while the respective moving objects are staying in the communication area. a beam forming processing unit configured to perform beam forming processing with a terminal provided in a moving object; a beam angle detection unit configured to detect a beam angle based on a result of the beam forming processing; and a moving object position estimation unit configured to estimate a position of the moving object based on the beam angle and installation position information of the data transmitting device, wherein the data transmitting device determines whether the estimated position of the moving object is within a communication area of the data transmitting device, and wherein the data transmitting device transmits desired data to the moving object if it is determined to be within the communication area, wherein the data transmitting device fragments the desired data pursuant to an allowable transmission unit and transmits the fragmented data, wherein the moving object is a plurality of moving objects forming a prescribed group, wherein with respect to one of the plurality of moving objects forming the group, the data transmitting device determines whether it is possible to complete transmission of the data while the one of the plurality of moving objects is staying in the communication area based on the estimated position of the moving object and a size of the data, wherein the data transmitting device fragments the data if it is determined that it is not possible to complete the transmission of the data while the one of the plurality of moving objects is staying in the communication area, and wherein the data transmitting device transmits different fragments of the data to the one of the plurality of moving objects and other moving objects forming the group, respectively, while the respective moving objects are staying in the communication area.