Three-way stopcock

The stopcock body (2) is provided with a cylindrical part (15), a first port (11), a second port (12) and a third port (13) which communicate with the cylindrical part (15), and a cock (20) rotatably inserted into the cylindrical part. By causing the cock to rotate within the cylindrical part, the rotated position of the cock can be switched between at least a first position at which the second port and the third port communicate, a second position at which the first port and the third port communicate, and a third position at which the first port and the second port communicate. A stopper (4) which is provided with a first restricting part (45a) and a second restricting part (45b) for restricting the range of rotation of the cock by coming into abutment against the cock is installed in the stopcock body.