A medical stopcock includes a main body and a cock. The main body includes: a tubular portion an upstream port and a downstream port and a bypass port provided between the upstream port and the downstream port. The cock includes: a cylindrical portion rotatably accommodated in the tubular portion of the main body and a handle configured to allow rotation of the cylindrical portion. The cylindrical portion includes: a first flow path groove communicating with the upstream port and the bypass port when the cock is in a reference position, a second flow path groove communicating with the bypass port and the downstream port when the cock is in a reference position, at least one wall portion closing openings of the upstream port, the bypass port and the downstream port when the cock is rotated by a predetermined amount from the reference position.
