A working unit of a manipulator includes a hollow joint shaft, wires disposed as power transmitting members in the hollow joint shaft, and a distal-end working unit mounted on an end of the hollow joint shaft and movable by the wires. The wires are wound around respective tubular members in the distal-end working unit. The hollow joint shaft has a pair of visual checking holes defined in respective side walls thereof near the distal end thereof for allowing the wires to be visually checked therethrough. The visual checking holes are positioned to expose the tubular members therethrough.
