Image Reading Apparatus

An image reading apparatus includes a document placing table having a transparent member, a document pressing member, an image reading unit, a scanning unit that is disposed on a side opposite to a document placing surface of the transparent member and reciprocates in a predetermined direction along the transparent member with the image reading unit mounted thereon, an open/closed state detecting unit that detects open and closed states of the document pressing member, a control unit that controls an image reading operation of the image reading unit and a reciprocation movement of the scanning unit, and a reference member that serves as a luminance reference of the image reading unit. When the open/closed state detecting unit detects the open state of the document pressing member, the control unit set a predetermined light intensity set value to a light intensity value of light irradiated from the light source at the time of image reading.