PURPOSE: To commonly utilize the optical mark reader to a mark sheet with different center point space distance of a mark by relatively positioning a sensor unit group and a space setting body in the cross direction against the longitudinal direction of a groove.

CONSTITUTION: Plural mark sensors 3 are individually supported movably in the right and the left direction in a rail 7 equipped with a board 4. When a sensor unit group 8 are positioned in the center of a groove 10 in a space setting body 9, the space of the individual mark sensor 3 becomes 0.25l. When the sensor unit group 8 are positioned on the upper groove side of the groove 10, the space of the mark sensor 3 becomes 0.3l. Similarly, when positioned on the upper side of the groove 10, the space of the mark sensor 3 becomes 0.2l. Thus, the reading of the mark sheet with different distance between the center point space of the mark can be realized.