PURPOSE: To provide the optical unit of a picture reader in which the distortion of a picture can not be generated by reducing the shake of a traveling body at the time of picture reading.

CONSTITUTION: Two slide shoes 9 fixed to the other side of a traveling body 1 (or 2) are arranged in a direction vertical to the sliding direction of the traveling body with a gap at an (t) interval, and the two slide shoes 9 are allowed to slide on the different sliding surfaces of a guide rail (not shown by a figure). Thus, the friction of three shoes 9 (the slide shoe at the other side is not shown by a figure) fixed on the both sides of the traveling body 1 (or 2) can be made uniform, and the shake of the traveling body 1 (or 2) at the time of picture reading can be reduced.