A sheet feeding device includes an elastic support member, a following
movable member disposed so as to contact an uppermost sheet of a stack of
sheets stacked on a sheet tray and can follow and move in accordance with
the change in the stacking amount of the sheets, a restraining mechanism
that restrains the elastic support member in accordance with the stacking
amount of the sheets so that the position of the uppermost sheet is held
at a substantial constant, and a release mechanism that interlocks with
the movement of the following movable member to release the restrained
state. The restraining mechanism includes an engagement member that moves
together with the elastic support member and a restraining member that
restrains the movement of the engagement member. The restraining member
moves along a straight locus at least near an engaging portion to engage
with and disengage from the engagement member.