In a data transmission terminal, a processor is configured to determine whether or not a change greater than or equal to a predetermined amount has occurred between values represented by multiple pieces of first sensor data stored on a memory when a state of communication has shifted from a normal state to a disconnected state. The processor is configured to classify the multiple pieces of the first sensor data as changed data and unchanged data when the processor determines that the change has occurred. The processor is configured to transmit the changed data to the external terminal by using a communicator. The processor is configured to transmit the unchanged data to the external terminal by using the communicator after the changed data are transmitted to the external terminal.