Problem to be solved: to provide an extendible working machine which is lightweight and which has a rod section capable of being extended longer. Solution: an extendible working machine is provided with a rotation/drive section, a working section, and a rod section which connects the rotation/drive section and the working section, transmits rotational force to the working section, and can be extended and retracted. The rod section is provided with a tube body which can be extended and retracted, and also with a shaft body which extends in the axial direction within the tube body and which can be extended and retracted together with the tube body. The tube body is provided, with an outer tube and with an inner tube which can move within the outer tube. The shaft body is provided with a drive shaft which is supported within the outer tube by bearings in a rotatable manner, and also with a pipe shaft which is supported within the inner tube in a rotatable manner. Helical grooves are formed in the surface of the drive shaft, and the drive shaft is connected to the pipe shaft such that the pipe shaft can move in the axial direction along the outer surface of the drive shaft and such that the rotation of the drive shaft is transmitted to the pipe shaft.