To provide a two-wire measuring instrument that can be powered stably and is highly functional.

The two-wire measuring instrument, which comprises sensor circuits for measuring process values, a digital circuit for arithmetically processing the outputs of the sensor circuits, and an output current control circuit for controlling a current through a first external power supply according to the output of the digital circuit, is provided with a pulse output circuit for outputting a pulse or status to a second external power supply different from the first external power supply, and a pulse current supply circuit connected in parallel with the pulse output circuit to control the voltage of the second external power supply and supply it to the junction between the sensor circuits and digital circuit and the output current control circuit.