Image reading device having a rectangular-shaped opening on a side of a reading target, wherein long sides of the rectangular shaped opening including a first layer, a second layer and an interface between the first layer and the second layer that has an arched shape warping from a center portion of the rectangular-shaped opening

An image-reading apparatus comprising:

• a housing having a rectangular-shaped opening on a side of a reading target;
• a lens portion retained or housed within the housing;
• and
• a sensor element to receive light condensed by the lens portion, the light being from the reading target,
• wherein
• walls of the housing form long sides of the rectangular-shaped opening include a first layer and a second layer disposed in order from the side of the reading target,
• the first layer has a surface that is flat on the side of the reading target, and
• an interface between the first layer and the second layer is curved to be in an arched shape warping from a center portion of the rectangular-shaped opening in a direction of the long sides.