To provide a paper sheet end face regulating mechanism in which a design change for each shipping destination is not necessary, usability is not impaired comparing to the conventional mechanism, and erroneous setting of a paper sheet regulating member by a user can be more surely prevented, and a paper feeding cassette capable of reducing paper jams in an image forming device by surely preventing the erroneous setting of the paper sheet regulating member by the user without drastically changing the design of the conventional paper feeding cassette.

A guide part 11 provided on a paper sheet loading face 10 has a locking part 14 for the centimeter system for positioning and fixing the paper sheet regulating member 20 corresponding to a paper sheet of centimeter system size on one side, and similarly has a locking part 15 for the inch system on the other side. Engaging members 22, 23 having an engaging part respectively engaged with the locking parts 14, 15 are mounted on a guide plate 21 so as to turn around a rotary shaft 27. The mechanism is applied to the paper feeding cassette.