An image forming apparatus includes first and second feeding units for feeding a recording material while nipping the recording material; a guiding member for guiding the recording material passed through the first feeding unit toward the second feeding unit; a measuring unit for measuring a time required for the recording material to pass from a first point to a second point provided downstream of the first point with respect to a recording material feeding direction; and a discriminating unit for discriminating stiffness of the recording material on the basis of a measurement result of the measuring unit. The guiding member is flexed and is in a non-overlapping state with a virtual line connecting a first nip where the first feeding unit nips the recording material and a second nip where the second feeding unit nips the recording material.