PURPOSE: To prevent reduction in resolution due to level difference of a signal from a coordinate indicator by inputting a scanning address to an analog circuit.

CONSTITUTION: A sense line 1 of a coordinate reader is scanned sequentially by an X axis scanning circuit 4a and a Y axis scanning circuit 4b by using a scanning address 3 transmitted from a control circuit 2. The scanned sense line detects a signal outputted from a coordinate indicator 6 driven by a drive circuit 5 and inputted to an analog circuit 7 via the scanning circuits 4a, 4b. A signal 15 detected by the analog circuit 7 is converted into a digital signal 9 by an A/D converter 8 and the X and Y axis coordinates are operated by allowing the control circut 2 to compare the said values. Then a scanning address 3a for selecting the X and Y axis sense lines among the scanning addresses 3 is given to an analog circuit 7, an analog switch 14 is turned on and its amplification factor is controlled to eliminate the signal level difference detected from the X and Y axis sense lines.