PURPOSE: To provide a robot main body, which can perform the work of two robots in a location space for one robot.

CONSTITUTION: In the rectangular coordinate type robot main body, two ball screw shafts 4, 5 to be respectively driven by motors 11, 12 are arranged in parallel with each other in the horizontal direction, and ball screw nuts 6 (,7) engaged with the ball screw shafts 4, 5 are respectively fixed to a first movable carriage 8 and a second movable carriage 9, and two movable carriages 8, 9 to be operated separately from each other by a separate driving system on the same track are provided, and furthermore, motors 11, 12 are arranged under the X-axial frame 2. With this structure, two kinds of work can be performed by one robot, and in comparison with the case of using two robots, equipment cost is reduced, and location space is reduced. Furthermore, since length of the X-axial unit is short, assembly line is shortened at the time of assembling the X-axial unit in an automatic assembly line.