The present invention is a medical stopcock (1) including a main body (2) and a cock (3). The main body (2) has a tubular portion (21), an upstream port (22), a downstream port (23) and a side pipe port (24). The cock (3) has a cylindrical portion (31) and a handle (32). A groove portion (33) is provided on an outer peripheral surface of the cylindrical portion (31). Wall portions (34a) and (34b) functioning as a part of the outer circumferential surface are disposed in an inside of the groove portion (33).
