A three-port valve that can be more accurately controlled using a simple structure. The three-port valve is provided with the following: a first elastic tube in which a liquid circulates; a first port which is a provision and discharge opening in the first elastic tube; a second elastic tube in which a liquid circulates; a second port which is a provision and discharge opening in the second elastic tube; a third port that links the first port and the second port; first circulation control means for deforming the first elastic tube so as to control the circulation of the liquid circulating in the first elastic tube; second circulation control means for deforming the second elastic tube so as to control the circulation of the liquid circulating in the second elastic tube; and an oscillator for driving the first circulation control means and the second circulation control means.