To provide a position detecting device which has high detecting accuracy despite its simple constitution.

The signals which are received from a position indicator A of a position detecting device B are detected at a sensor part 21, held by a sample-and-hold circuit 29 via a transmission/reception switching circuit 25, a receiving operational amplifier 26, a detection circuit 27 and a low pass filter 28 and then converted into the digital signals by an A/D (analog/digital) converter 30. These digital signals undergo the arithmetic processing via a CPU 31 and the coordinate position of the indicator A is calculated. Meanwhile, the largest voltage that is outputted from the circuit 29 in the preceding scanning mode is held by a peak holding circuit 32, and the voltage conversion range of the converter 30 varies according to true said largest voltage. Thus, the converter 30 is set at a point near its voltage conversion range and the highly accurate position detection is attained.