The invention belongs to the technical field of design and manufacturing of parts in coal mine drilling machines, particularly relates to a manipulator automatic stem changing device for a undergrounddrilling machine to solve the problems that manipulator grasping stem is adopted but accuracy is low, and the structure of a drilling stem cabin is not reasonable, so that error is large during manipulator grasping, and therefore efficiency is low during cooperating use. The manipulator automatic stem changing device comprises a drilling machine, a drilling stem cabin device, a manipulator rotating device, a holder and a drilling machine fixing seat. The drilling machine is mounted at one end of the drilling machine fixing seat; the drilling stem cabin device used for storing a drilling stemis mounted on the drilling machine fixing seat; the manipulator rotating device used for taking out the drilling stem rotating to the working position is mounted on the drilling machine fixing seat; and the holder is mounted at the other end of the drilling machine fixing seat. Automatic stem grasping, stem placing and reverse operation in stem withdrawing process are achieved. The drilling stem cabin device controlled by a double-ratchet wheel is provided, and grasping accuracy is greatly improved.