A robot arm assembly with tubes or pipes carrying fluids or electrical cables which do not get bent and are relatively straight, and are not disrupted by, the moving parts of the robot arm includes a first robot arm, a second robot arm, a third robot arm, and a flexible carrying tube. The second robot arm includes a first axle base, a first input shaft, a first bevel gear, and a second bevel gear. The flexible tube is inserted into the first bevel gear and the second bevel gear along a first axis, and fixed to the output shaft.