<p>A data collection system includes: a server (7) connected to the Internet (6); a plurality of data acquisition target devices (1); and a plurality of data transfer devices (3) that can be connected to the data acquisition target devices, respectively. Device data acquired by each data transfer device from each data acquisition target device are transferred to the server via the Internet using a mobile phone (5). The data transfer device includes: a data acquisition part (13) for acquiring the device data from the data acquisition target device; a data transfer part (14) for combining transmission instruction data with the device data so as to generate transfer data, and transferring the transfer data to the mobile phone; and a control part (15) for allowing the operation of acquiring the device data and the operation of transferring the transfer data to be executed. The transmission instruction data correspond to an instruction to the mobile phone to perform an operation of transmitting the device data to a predetermined server.</p>
