To provide a caster unit and a carry bag which can individually or freely change a wheel or a caster mechanism without lowering the solidity of the wheel or the caster mechanism itself.

The caster unit takes a curve form along the outer peripheral edge of the bottom part of a bag and includes at least a plurality of rivet insert holes and has a plurality of female screw insert holes made of metal, a plurality of female screw attaching holes to which female screws made of metal are attached and a wheel unit freely rotating in a vertical direction and a horizontal direction.