The injector of the present invention (10) comprises a heat-retaining tube (12), an outer pipe (18) for inserting into a uterus which is fixed parallel to a front end of the heat-retaining tube (12), a syringe (22) for injection inserted into the heat-retaining tube (12) from the rear end of the heat-retaining tube (12), an elastic and flexible tube for injection (24) which is connected to the front end of the syringe (22) and is pulled out of the front end of the heat-retaining tube and is inserted slidably into inside of the hollow of the outer pipe (18),and a discharge nozzle (28) which is mounted integrally to the front end of the tube (24) and projects from the front end of the tube (18), and in which a portion between a projecting position from the heat-retaining tube (12) and the outer pipe (18) is regarded as a surplus length portion (24a) and the surplus length portion (24a) is paid out in a state that the outer pipe (18) is inserted to a given depth in a uterus, thereby making the discharge nozzle (28) reach to the deep portion of the uterus along the shape of the uterus.