A processing apparatus comprising: a processing unit is configured to perform a predetermined process on a medium; a placement unit on which the medium can be placed in a first posture in which a surface of the medium is placed along a placement surface of the placement unit; a medium feeding unit configured to feed the medium from the placement unit toward the processing unit; and a feed unit that is detachably disposed on the placement unit, wherein the feed unit is configured to cause the medium to be placed in a second posture which is different from the first posture in which, of four sides of the medium, an end side on a downstream side in a transport direction is brought into contact with a placement surface of the feed unit and the medium is inclined; characterised in that the medium feeding unit has a first gear on a shaft of a feed roller which is one constituent member, and the feed unit has a second gear, wherein the first gear and the second gear intermesh with each other with the feed unit disposed on the placement unit, the feed unit further includes a roller configured to feed the medium toward the medium feeding unit, and the roller is configured to rotate, with power from the medium feeding unit transmitted thereto via the first gear and the second gear; wherein the medium having the first posture can be fed out by the medium feeding unit in a state in which a surface of the medium is placed along the placement surface of the placement unit, configured such that, when the medium having the second posture moves to a position of the roller and passes through the position of the roller, with the end side of the medium on the downstream side sliding on the placement surface of the feed unit, the posture of the surface of the medium changes along the placement surface of the feed unit, and the medium is fed to the medium feeding unit by the roller. a processing unit is configured to perform a predetermined process on a medium; a placement unit on which the medium can be placed in a first posture in which a surface of the medium is placed along a placement surface of the placement unit; a medium feeding unit configured to feed the medium from the placement unit toward the processing unit; and a feed unit that is detachably disposed on the placement unit, wherein the feed unit is configured to cause the medium to be placed in a second posture which is different from the first posture in which, of four sides of the medium, an end side on a downstream side in a transport direction is brought into contact with a placement surface of the feed unit and the medium is inclined; characterised in that the medium feeding unit has a first gear on a shaft of a feed roller which is one constituent member, and the feed unit has a second gear, wherein the first gear and the second gear intermesh with each other with the feed unit disposed on the placement unit, the feed unit further includes a roller configured to feed the medium toward the medium feeding unit, and the roller is configured to rotate, with power from the medium feeding unit transmitted thereto via the first gear and the second gear; wherein the medium having the first posture can be fed out by the medium feeding unit in a state in which a surface of the medium is placed along the placement surface of the placement unit, configured such that, when the medium having the second posture moves to a position of the roller and passes through the position of the roller, with the end side of the medium on the downstream side sliding on the placement surface of the feed unit, the posture of the surface of the medium changes along the placement surface of the feed unit, and the medium is fed to the medium feeding unit by the roller.