PURPOSE: To select a measuring item automatically by supplying an encode signal corresponding to the condition of a point to be measured to a converter for making the converter conduct its desired function.

CONSTITUTION: In measuring a circuit of unknown parameter, an input terminal 60 or a testing lead is connected to a point to be measured or a node. If live voltage large enough to operate a detection circuit 62 exists at these points to be measured, the circuit 62 supplies a signal appropriate to indicate this condition to an encoder 68. The encoder 68 generates encode signals B0, B1 and B2, controls a converter 64 so as to measure AC voltage or DC voltage detected by the circuit 62 to make an indicator 66 display the measuring results of a resistor. If the live voltage is not present, the measuring results of the resistor are displayed on the indicator 66 according to the operation of the circuit 62 and the encoder 68. By detecting a supply signal to a multimeter and supplying an encode signal to the converter, it is possible to select a prescribed measuring item from many functions.