A Highway Addressable Remote Transducer, HART analog input module with a differential input stage, the HART analog input module comprising: a plurality of input stage processors (210, 220, 230, 240) respectively connected to a plurality of HART field devices (110, 120, 130, 140) to detect a DC signal and a HART communication signal from an input signal and output the DC signal and the HART communication signal, in a case the HART communication signal superimposed on top of the DC signal is inputted from a relevant HART field device (110, 120, 130, 140); an analog multiplexer configured to sequentially output the DC signal of each channel outputted from each input stage processor (210, 220, 230, 240) to an A/D conversion processor in response to a control signal; an A/D conversion processor configured to convert the DC signal of each channel sequentially outputted from the analog multiplexer to a digital signal; an HART multiplexer configured to output the HART communication signal of each channel outputted from the each input stage processor (210, 220, 230, 240) to a HART modem in response to the control signal; an HART modem configured to demodulate the HART communication signal of each channel sequentially outputted from the HART multiplexer; and a controller configured to provide the control signal to the analog and the HART multiplexers (250, 270) and process the digital signal outputted from the A/D conversion processor and the HART modem, characterized in that: the each input stage processor (210, 220, 230, 240) includes an insulation ground terminal (S1B, S2B, S3B,S4B) configured to allow output of the DC signal as a differential signal and to allow a ground potential used for recognition of the HART communication signal to be equal to a ground potential (AG1, AG2, AG3, AG4) of the relevant HART field device(110, 120, 130, 140). a plurality of input stage processors (210, 220, 230, 240) respectively connected to a plurality of HART field devices (110, 120, 130, 140) to detect a DC signal and a HART communication signal from an input signal and output the DC signal and the HART communication signal, in a case the HART communication signal superimposed on top of the DC signal is inputted from a relevant HART field device (110, 120, 130, 140); an analog multiplexer configured to sequentially output the DC signal of each channel outputted from each input stage processor (210, 220, 230, 240) to an A/D conversion processor in response to a control signal; an A/D conversion processor configured to convert the DC signal of each channel sequentially outputted from the analog multiplexer to a digital signal; an HART multiplexer configured to output the HART communication signal of each channel outputted from the each input stage processor (210, 220, 230, 240) to a HART modem in response to the control signal; an HART modem configured to demodulate the HART communication signal of each channel sequentially outputted from the HART multiplexer; and a controller configured to provide the control signal to the analog and the HART multiplexers (250, 270) and process the digital signal outputted from the A/D conversion processor and the HART modem, characterized in that: the each input stage processor (210, 220, 230, 240) includes an insulation ground terminal (S1B, S2B, S3B,S4B) configured to allow output of the DC signal as a differential signal and to allow a ground potential used for recognition of the HART communication signal to be equal to a ground potential (AG1, AG2, AG3, AG4) of the relevant HART field device(110, 120, 130, 140).