To prevent the occurrence of any impact noise in time of paper feeding without entailing any damage to the conveyability of paper.

This paper feeding mechanism is provided with a paper loading plate 42 loading the stacked sheets of paper 11, a semilunar paper feed roll 13 feeding an image forming part with the paper 11 piece by piece, a cam 60 equipped with a large diametral part and a small diametral part 60E, and a lever 48 equipped with an engaging part 48B being engaged with a lock part 48C, respectively. A gravitational center BW of this cam 60 is situated nearly on a line connecting an axial center QX and a maximum radius RZ of the cam 60. When the paper feed roller 13 gets feeding the paper, the cam 60 will gently come into pressedly contact with the paper 11 with movements of the gravitational center BW. Since the paper 11 will smoothly shift from the large diametral part to the small diametral part 60E of the cam 60, the engaging part 48B smoothly comes into contact with the part 48C, whereby an impact is buffered, preventing any impact noise from occurring. In addition, since an impact to be transmitted to a sensitive drum or the like is prevented, an image is made up in a stable state.