The suction / discharge unit 11 of the suction / discharge device 10 includes a first unit 21 and a second unit 22. The second unit 22 controls the pressure inside the first unit 21. The first unit 21 includes a storage chamber 41 and a water seal chamber 42, and the water seal chamber 42 is sealed from the first chamber 42 a by the first chamber 42 a communicating with the storage chamber 41 and the sealing water 36. Second chamber 42b. A negative pressure control unit 50 is disposed in the second chamber 42b. The negative pressure control unit 50 includes a liquid storage unit that stores the liquid 54, a control member 52 having a control hole 52 <；/ b>； X, and a support cylinder 53 that supports the control member 52. The negative pressure control unit 50 causes gas to flow from the second chamber 42b to the first chamber 42a through the control hole 52X and the liquid 54 based on the pressure in the second chamber 42b and the pressure in the first chamber 42a. To control the pressure in the first chamber 42a.
