A document scanning apparatus for scanning a document is provided. The document scanning apparatus includes an image sensor unit which irradiates an incident light towards the document and generates image data by sensing a reflected light reflected from the document, a supporting unit which supports the image sensor unit, a movement unit which moves the image sensor unit between a scanning position and a calibration position, a housing which houses the image sensor unit, the supporting unit, and the movement unit, a transparent plate which transmits the incident light and the reflected light, a calibration sheet which is attached to a surface of the transparent plate, which is exposed to outside and is positioned in an area including the calibration position, and a housing cover which is coupled to the housing and seals inside of the housing.