IMAGE-READING DEVICE COMPRISING A PLURALITY OF OPTICAL COMPONENTS ARRANGED ALONG THE SCANNING DIRECTION AND HOUSING COMPONENTS ARRANGED TO HAVE A FIRST CLEARANCE THEREBETWEEN

An image reading device includes a board including a plurality of imaging elements arranged along a scanning direction, and a housing including a plurality of optical components that are arranged along the scanning direction and a plurality of housing components that are arranged along the scanning direction. Each of the plurality of optical components focuses light reflected by a reading target onto a corresponding imaging element, and each of the plurality of housing components holds at least one optical component. The plurality of housing components are arranged to have a clearance therebetween and each of the plurality of housing components is fixed to the board at a position to transmit light through the optical components to focus onto the corresponding imaging element.