To provide a sheet feeding device capable of reliably holding a regulating member to a regulating position without enlarging a paper feeding cassette, and an image forming device.

In this sheet feeding device, a first rack tooth train 1a and a second rack tooth train 1b constituting a holding mechanism for holding a position of a rear end regulating plate 5 to a regulating position corresponding to a sheet size are provided at an identical height along a sheet regulating direction on a bottom face 1B of a cassette body 1A, and a first tooth train 9a and a second tooth train 10a are provided at the regulating member 5 at an identical height along the sheet regulating direction.