To provide a cross bar attaching/detaching mechanism capable of suppressing occurrence of any torsional deformation of an arm for supporting an attaching/detaching mechanism body, and a workpiece conveying device having the same.

The cross bar attaching/detaching mechanism 50 comprises a pair of rods 52 to be respectively fitted to first hole parts formed in end faces 3s at both ends of a cross bar 3, a first actuator 54 for pressing the rods 52 against the cross bar 3, a pair of positioning pins 56 to be respectively fitted to second hole parts 3p formed in the end faces 3s at both ends of the cross bar 3, and a second actuator 58 for moving the positioning pin 56 toward the cross bar 3.