A medium discharge device includes a discharge drive roller configured to contact a first surface of a medium, a discharge driven roller that is configured to contact a second surface of the medium and nip the medium between itself and the discharge drive roller, a driven roller shaft, and a discharge assisting member configured to contact the second surface of the medium to be discharged, that has a larger diameter than the discharge driven roller, and that rotates integrally with the discharge driven roller. The discharge driven roller has a shaft hole through which the driven roller shaft passes, an inner peripheral surface of the shaft hole and an outer peripheral surface of the driven roller shaft slide with rotation of the discharge driven roller, and a quick-drying lubricant is used between the inner peripheral surface of the shaft hole and the outer peripheral surface of the driven roller shaft.