Cover component, image sensor unit, image reading apparatus, and paper type identification apparatus

The utility model provides a cover component, an image sensor unit, an image reading apparatus, and a paper type identification apparatus; and the precision of the parallelism degree of the cover component at the main scanning direction can be improved. The cover component (40) is characterized in that the cover component (4) comprises: a transmitting component (55), which is formed along the main scanning direction and enables the light emitted from a light source portion (20) to be transmitted; and a frame component (41), which is used for holding the transmitting component (55). The frame component (41) includes: long side frame portions (42a and 42b), which are formed along the main scanning direction; and protruding portions (48), which protrude from the inner side walls (47) of the long side frame portions (42a and 42b) towards the direction of the outer peripheral surface (57) of the transmitting component (55). Under the circumstances that the transmitting component (55) and the frame component (41) are not in contact with each other, adhesives filling the space between the inner peripheral surfaces, being vertical surfaces 48a, of the protruding portions (48) and the outer peripheral surface (57) of the transmitting component (55) are used for combining the transmitting component and the frame component.