The utility model provides a paper feeder and image forming device, this paper supply device include the paper feeding cassette of splendid attire medium, will in the paper feeding cassette the mediumis rubbed with the hands out rubs the paper roll with the hands, to rubbing with the hands out the alignment roller that the medium aligns and operates the upstream side movable mounting of alignmentroller has a rotatable brake pads the brake pads is kept away from the detection is installed to medium transport passageway one side brake pads turned angle's angle sensor. The utility model discloses can be when the medium align the operation, set aside factors such as the material of medium itself, moist, basic weight and kind, only detect to its crooked volume, the existing reservation of cooperation that can the be fine requirement of aliging makes different media reach optimalizing alignment volume, can avoid the medium to harm moreover.