A specimen transport unit, wherein the specimen transport unit includes and drives: - a plurality of transport lines for driving belts to transport specimen racks on which a specimen container is disposed, - a single driving motor having a rotating shaft, - a shaft (33a, 33b) for transmitting power of the driving motor, - a plurality of pulleys (41, 42, 43) for transmitting rotation of the shaft (33a, 33b) to the belts to drive the belts, and - the belts of the plurality of transport lines by rotatably driving the pulleys, wherein: the transport lines include: - an upper transport line provided at an upper stage; - a first pulley for driving the upper transport line; characterised in that the transport lines include: - a lower transport line provided at a lower stage; - a second pulley for driving the lower transport line; and in that said first pulley and said second pulley are provided in both ends of the shaft (33a, 33b), wherein: the upper transport line includes: - a main transport line for transporting, in one direction, a specimen to be processed and - a return line for transporting, in a direction opposite to the direction of the main transport line, a specimen that has been processed; the shaft includes: - a first shaft for transmitting power to the main transport line and - a second shaft for transmitting power to the return line; wherein the first shaft and the second shaft are attached to the driving motor so as to be rotatably driven in opposite directions, wherein - the lower transport line includes a first empty specimen rack transport line for transporting an empty specimen rack and - a second empty specimen rack transport line driven in a direction opposite to the direction of the first empty specimen rack transport line; wherein the first shaft drives the first empty specimen rack transport line and the second shaft drives the second empty specimen rack transport line. - a plurality of transport lines for driving belts to transport specimen racks on which a specimen container is disposed, - a single driving motor having a rotating shaft, - a shaft (33a, 33b) for transmitting power of the driving motor, - a plurality of pulleys (41, 42, 43) for transmitting rotation of the shaft (33a, 33b) to the belts to drive the belts, and - the belts of the plurality of transport lines by rotatably driving the pulleys, the transport lines include: - an upper transport line provided at an upper stage; - a first pulley for driving the upper transport line; - an upper transport line provided at an upper stage; - a first pulley for driving the upper transport line; characterised in that the transport lines include: - a lower transport line provided at a lower stage; - a second pulley for driving the lower transport line; - a lower transport line provided at a lower stage; - a second pulley for driving the lower transport line; and in that said first pulley and said second pulley are provided in both ends of the shaft (33a, 33b), wherein: the upper transport line includes: - a main transport line for transporting, in one direction, a specimen to be processed and - a return line for transporting, in a direction opposite to the direction of the main transport line, a specimen that has been processed; the shaft includes: - a first shaft for transmitting power to the main transport line and - a second shaft for transmitting power to the return line; wherein the first shaft and the second shaft are attached to the driving motor so as to be rotatably driven in opposite directions, wherein - the lower transport line includes a first empty specimen rack transport line for transporting an empty specimen rack and - a second empty specimen rack transport line driven in a direction opposite to the direction of the first empty specimen rack transport line; wherein the first shaft drives the first empty specimen rack transport line and the second shaft drives the second empty specimen rack transport line. the upper transport line includes: - a main transport line for transporting, in one direction, a specimen to be processed and - a return line for transporting, in a direction opposite to the direction of the main transport line, a specimen that has been processed; - a main transport line for transporting, in one direction, a specimen to be processed and - a return line for transporting, in a direction opposite to the direction of the main transport line, a specimen that has been processed; the shaft includes: - a first shaft for transmitting power to the main transport line and - a second shaft for transmitting power to the return line; - a first shaft for transmitting power to the main transport line and - a second shaft for transmitting power to the return line; wherein the first shaft and the second shaft are attached to the driving motor so as to be rotatably driven in opposite directions, wherein - the lower transport line includes a first empty specimen rack transport line for transporting an empty specimen rack and - a second empty specimen rack transport line driven in a direction opposite to the direction of the first empty specimen rack transport line; - the lower transport line includes a first empty specimen rack transport line for transporting an empty specimen rack and - a second empty specimen rack transport line driven in a direction opposite to the direction of the first empty specimen rack transport line; wherein the first shaft drives the first empty specimen rack transport line and the second shaft drives the second empty specimen rack transport line.