Image reading device and image forming apparatus

An image reading device comprising:

• a first reader member that reads an image recorded on a surface of a medium traveling through a read area by receiving light from the medium, the read area being set on a transport path along which the medium is transported and the read area has a first side perpendicular to a transport direction;
• an optical system that guides the light from the medium to the first reader member;
• and
• a second reader member having a color measurement unit that is disposed in an optical path of the light guided by the optical system and that performs color measurement on the light, the second reader member reading a color of the image recorded on the surface of the medium on the basis of the light, the second reader member reading the color of the image in a second area included in the read area read by the first reader member and the second area has a second side perpendicular to the transport direction, the second side shorter than the first side.