PURPOSE: To improve the resolution of phases by providing the coordinate reader with a data conversion part for outputting two phase binarizing signals obtained by multiplying two phase sinusoidal signal periods by N while holding their phase difference based upon phase angle information.

CONSTITUTION: Two phase sinusoidal signals 1a, 1b consisting of (a) and (b) phases are outputted from an incremental encoder 1. The data conversion part 3 for outputting two phase binarizing signals 6a, 6b obtained by multiplying two phase sinusoidal signal periods by ten while holding their phase difference based upon phase angle information obtained from two outputs 4a, 4b outputted from respective A/D conversion parts 4A, 4B are constituted of a ten fold table ROM 5 constituting a memory part for arraying data in order to output N = 10 multiplied two-phase binarizing signals while holding their phase difference and J-K flip flops 6A, 6B. These signals 6a, 6b are inputted and counted up to/by an inserting circuit 7 to obtain 1/40 resolution of the (a) and (b) phases. Thus, the resolution can be improved.