A reading device and an image forming apparatus. The reading device includes a reader disposed at a scanning position, the reader being configured to read an image formed on a surface of a sheet, a movement mechanism to move the reader between the scanning position and a separated position away from the scanning position, and a reference plate disposed at a first position facing a reading face of the reader, the reference plate being configured to obtain a reference value to be used when the reader reads the image. In the reading device, the reference plate rotates around an axis from a second position facing a side of the reader to the first position or from the first position to the second position in conjunction with movement of the reader from the scanning position to the separated position by the movement mechanism The image forming apparatus includes the reading device.