To construct a system at a lower cost by which a phenomenon or a state to be measured is automatically recorded or monitored.

A log terminal 10 is provided with a measuring part 34 for measuring a signal from a sensor at sampling intervals and obtaining measurement data, a recording part 34 for recording the measurement data in a memory 34a at recording interval, a monitor part 36 for comparing measurement data with an upper limit value or a lower limit value, a report part 37 for outputting a report and an output part 38 for receiving a command which indicates the transmission of recording data to the telephone number of the log terminal, performing a report via a modem 12 which specifies the telephone number by a reception destination and outputting recording data which is recorded in the memory to the prescribed reception destination. Since the log terminal 10 is the terminal where functions required for automatic measurement such as measuring, recording, monitoring, reporting and communicating are packed in one body, a data logger system is constructed only by connecting the sensor.