The present invention relates to a direct drive motor-based wafer transfer robot device, wherein an in-chamber wafer transfer robot comprises: a hand module including hands capable of loading a wafer on one side thereof through ends of first and second hand arms, and the hand arms which are coupled to the hands and transport the wafer; an R-axis module which includes a central shaft having one end coupled to the hand arm, a rotary motor member coupled along the outer circumference of the central shaft, a fixed motor member fixed to the outer circumference of the rotary motor member, and a cylindrical vacuum-blocking thin film which is disposed between the rotary motor member and the fixed motor member and vacuum-isolates the inside thereof, the R-axis module providing motive power to the hand module through the rotary motor member; a connecting enclosing module having one end coupled to the R-axis module; and a T-axis module which includes a central rotational shaft which is rotatably coupled to the connecting enclosing module at the other end of the connecting enclosing module, a magnetic fluid seal surrounding the outside of the central rotational shaft, and a motor which is disposed along the lower outer circumference of the central rotational shaft and provides a rotational force on the central rotational shaft.