PURPOSE: To avoid any possible drop in rail accuracy attributable to accuracy in a supporter by installing a crosstied supporter after rectilinear accuracy in a rail high in rigidity.

CONSTITUTION: Rails 2 support a travel base 4 in an industrial robot with this travel base 4 and guides its travel. A number of crosstied supporters 8 are clamped each to the rail 2 and set up in crossing this rail 2 as separating from each other. With this constitution, any possible drop in rail accuracy attributable to acciracy in each supporter 8 is thus avoidable. Therefore, even if a rail installing surface is not machined, the required travel accuracy of the industrial robot is easily securable and, what is more, the manufacturing cost is thus reducible.