To allow an operator to freely walk on a floor in a workpiece carrying and assembling apparatus which carries a workpiece and assembles parts to the workpiece.

A slit is formed on a floor. A conveyor is installed under the slit. Conveyor dogs 40 are attached to a chain 33 of the conveyor at required intervals. A rear member 42 of the conveyor dog 40 engages with a front member of the conveyor dog 40 so as to turn in the horizontal plane and the vertical plane. The rear member 42 is provided with an engagement member. A push rod member 56 extending downward through the slit is provided under a bottom plate of a carriage 50 which can move on the floor by means of casters 54. As the conveyor moves, the push rod member 56 is pushed by the engagement member, and the carriage is carried on the floor. Parts are assembled to the workpiece mounted on the carriage.