To provide a paper sheet separating mechanism for a paper feeding device preventing frequent overlapping feed due to sudden reduction of friction coefficient of a retard roller and generation of paper powder due to deterioration of retard roller's co-rotation property with following a paper feeding roller (or paper sheet).

This paper separating mechanism has the retard roller 8 capable of rotating regular rotation direction and reverse rotation direction and elastically energized in the reverse rotation side by an elastic member provided with touching the paper feeding roller 7 rotating in the regular rotation direction. The paper feeding roller 7 and the retard roller 8 are made of urethane rubber. Hardness of the paper-feeding roller 7 is set in a range of JIS A 45 to 60 Hs and hardness of the retard roller 8 is set in a range of JIS A 65 to 85 Hs.