Abstract. We present the development of an innovative device (Stem Cell Harvesting Manipulator) to get a donor's hematopoietic stem cells for bone marrow transplantation with minimal puncture. In this paper, we report the development of a prototype of the manipulator with Flexible Drilling Unit. The manipulator is inserted into the medullary space from the iliac crest and aspirates the cells while an end-mill on the tip of the Flexible Drilling Unit drills through cancellous bone to create a curved path. We found that the manipulator could be inserted into the pig iliac bone 131 mm by 32.1 mm/min. Moreover, the number of harvested nucleated cells per puncture is 6.04 times more than the Aspiration Method. The Aspiration Method, however, could harvest much (3.73 times) denser graft than our method. Further consideration regarding whether or not this device can harvest viable hematopoietic stem cells should be considered through experiments using laboratory animals.