A medical stopcock which allows easier switching operation of plural branch-tubes. The main body of the stopcock comprises a chamber part with a nearly spherical inner surface, and an upstream branch-tube, a downstream branch-tube and a merge-branch-tube all extending from the chamber part. A valve body of the stopcock comprises a nearly spherical valve main body and a rod-shaped operating part with a guide hole linking the inner surface of the chamber part to the outside. In operation, the rod-shaped operating part is moved along the guide hole through the use of the horizontal flow passages and the vertical flow passage to allow the predetermined branch-tubes out of the upstream branch-tube, the downstream branch-tube and the merge-branch-tube to communicate with one another or to shut-off the communication.
