PURPOSE: To easily and accurately position an index by providing plural pulse dividing circuits which divide the pulses generated from a transducer at the different dividing rates and a switch which selects one of those pulse dividing circuits.

CONSTITUTION: The pulse dividing circuits 3a and 3b divide the pulses generates from the transducers 10a and 10b at the different rates. Then a switch 1 selects on of both circuits 3a and 3b. When an index is moved to a point B from a point A on a display, for example, a case 6 is moved without depressing the switch 1 and therefore the index is moved to a position near the point B. Then a push-button 1a is depressed once and the transducers 10a and 10b are connected to the circuit 3a via the switch 1. Then the case 6 is moved. At this time, the index has a small shift even if the case 6 is largely moved. Thus the index can be easily and accurately positioned.