The present disclosure relates to an image reading device, including: a light emitting portion; a light guiding member; a holding member that holds the light emitting portion and the light guiding member; and a case member that holds the holding member. In the image reading device, the light guiding member is shaped like a stick, of which end portion is disposed to face the light emitting portion. The holding member holds the light emitting portion and the light guiding member. In addition, the holding member has: and a holding portion that disposes the light guiding member along a main scanning direction, and positions and holds an end portion on the light emitting portion side in the main scanning direction. The case member holds the holding member.