Patent ID: 8622384

Claim:
A sheet processing apparatus comprising: a detachable sheet housing part in which a sheet is stacked; a placing plate which is installed in the detachable sheet housing part and moves as the sheet is stacked and housed therein; a magnetic body which is magnetized and is disposed on the placing plate; a magnetic sensor disposed on a stand, which detachably supports the detachable sheet housing part, the magnetic sensor detecting an amount of magnetism from the magnetic body; and a determination unit comprising a central processing unit, which determines whether the amount of magnetism detected by the magnetic sensor is greater than or equal to a threshold value or not; and a shield body disposed on a side of the detachable sheet housing part between the magnetic sensor and the magnetic body and extending along the side in a movement direction of the placing plate, wherein the magnetic body is moved with respect to the shield body as the placing plate moves and the threshold value is set in association with a position at which the magnetic sensor can detect the magnetism.