In order to provide an image reading apparatus of which a contact glass sheet can be replaced and recycled with ease without damaging the contact glass sheet when removing the same, and further intrusion of particles of dust into the apparatus when operating the apparatus can be prevented, an image reading apparatus having an image reading unit mounted to be able to be reciprocated in a frame body of the apparatus and a contact glass sheet is composed such that; the frame body comprises an upward-open lower frame in which the image reading unit is accommodated to be able to be reciprocated and an upper frame having an opening on the upper face thereof to be covered with the contact glass sheet, the upper and lower frames are assembled detachably by means of fitting portions provided to both frames, the contact glass sheet is attached to said upper frame by means of a strip-shaped adhesive member glued onto the undersurface of the upper frame along the brim part of the opening to be covered with the contact glass sheet, the strip-shaped adhesive member is glued onto the undersurface of the upper frame so that the strip is not continuous but partially interrupted to provide interrupted parts, and the glass sheet supports protruding from the lower frame are positioned to support the contact glass sheet at the position corresponding to the interrupted parts of the strip-shaped adhesive member.