PURPOSE: To provide a device for inspecting surface smoothness of roll which can efficiently inspect the surface of a roll in a short time, has a simple structure, and can be manufactured at a low cost and, at the same time, which does not give much burden to worker and can be automated.

CONSTITUTION: The device for inspecting surface smoothness of roll is provided with a reference drive roll 3 which has a smooth surface over the entire peripheral surface and is rotated by means of a driving motor 5, a pair of guide members 6 and 6 which hold the rotating shaft 2b protruded from both sides of a roll 2 to be inspected put on the roll 3 so that the roll 2 can be rotated above the rotating axis M of the roll 3, a projector 7a which is positioned on one side of the contact section S of the roll 2 with the roll 3 and can project light rays upon the contact section S over its full length, a photoreceptor 8 which is positioned on one side of the section S opposite to the projector 7, and a light shielding slit 9 which is provided between the photoreceptor 8 and roll 3, and a convex lens 10 provided between the slit 9 and photoreceptor 8.