To provide a carrier which can be easily modified to go straight when straight advance is required, in the carrier which freely advances in an arbitrary direction by fixing a support of an angled cross section around a rectangular quadrilateral flat plate, and by attaching an adjustable caster to the bottom end of each support.

A downward female screw is provided at the bottom end of each support, and the bottom end outer face of the female screw is made into a rectangular column, and projected from the support. A detent is newly provided, and the fixed section of the adjustable caster, the through-hole of a bolt for attaching the adjustable caster, and a notch for fitting the rectangle column around the through-hole are provided at the detent. The detent is fixed between the support and the adjustable caster.