Millimeter-waves are attractive as a broad-band transmission technology. In this paper, we discuss the millimeter-wave storage transmission system technology as a means of millimeter-wave broadband mobile communications in railways. First, we grasp the performance required for the millimeter-wave storage transmission equipment, sort the measurement results of the performance in railways, and exemplify the transmission system when used for track measurement. Second, we introduce the structure of millimeter-wave storage transmission equipment, and estimate the performance of the manufactured equipment to prove that it satisfies the required performance. Finally, we explain future subjects for the millimeter-wave data transmission of railway track measurement systems.