To make it possible for a traveling frame to effectively travel without deflecting to the right or left or the up or down to a surface platen, to accurately machine and to provide a simple structure with economic features.

Rail members 13 are fixed along a surface platen 12 onto a base 11. A traveling frame 20 has side frames 22. Upper rollers 23 as well as lower rollers and outer rollers 25 are respectively provided at the front and rear sides of the side frames. Drive rollers 27 driven the a drive motor 26 at the lower surface sides of the respective rail members and having a pressure contact wheel made of urethane rubber are vertically adjustably provided at the respective side frames.