PURPOSE: To make reliable usage possible even where the distance between a measurement place and a monitoring place is relatively long by constituting a measurement value detector as a transmitter.

CONSTITUTION: A transmitter 1 of a measurement value detector is divided into a power supply circuit 2, a high voltage/signal processing circuit 3 and an output circuit 4. A sensor (measurement tube) 5 is provided in the high voltage/signal processing circuit 3. The power supply circuit 2 comprises a power supply voltage terminal 6 of 2-terminal, a power supply voltage filter 7, a connection sleeve 8 of 1-terminal, being possible to remotely control the transmitter 1, for power supply continuation or shutdown, and light emitting diodes 9, 11 and 12. The high voltage/signal processing circuit 3 comprises a high voltage generating electronic element 13, a circuit module 14 which supplies a voltage to the element in the circuit 3, various circuit means 15 for signal processing and a measurement tube 5. In addition the output circuit 4 comprises a voltage supply means 16 for a constituent element and a current source 17. Since the detector is constituted as a transmitter, it can be used regardless of place of measurement value process.