In a valve-equipped hand switch and a chemical liquid introduction system, a contrast medium in a syringe is delivered to a patient line through a first port, a main passage around a spacer portion, and a second port. Furthermore, a pressure (about 300 psi) of the contrast medium delivered by a chemical liquid introduction device is transmitted as a reaction force through a third plunger from a handle portion of an operation piston held by an operator. As such, the operator can directly feel the pressure of the introduced contrast medium, which gives a sense of ease to the operator during operation.
