A pressure regulating apparatus comprising: a diaphragm including a cup-shaped pump portion; a pump chamber including a wall including the pump portion; a driving device connected to a bottom of the pump portion and configured to convert a rotation into a reciprocating motion and increase/decrease a capacity of the pump chamber; a motor configured to apply a rotational force to the driving device; a fluid inlet, a fluid discharge port, and a first exhaust port that are open to outside of the diaphragm pump; a suction passage configured to make the pump chamber communicate with the fluid inlet; a suction valve configured to open/close the suction passage to make a fluid flow from the fluid inlet toward the pump chamber in a process in which the capacity of the pump chamber increases; a discharge passage configured to make the pump chamber communicate with the fluid discharge port; a discharge valve configured to open/close the discharge passage to make the fluid flow from the pump chamber toward the fluid discharge port in a process in which the capacity of the pump chamber decreases; a first exhaust passage configured to make the first exhaust port communicate with an area in the discharge passage between a fluid outlet of the discharge valve and the fluid discharge port; a differential pressure regulating valve configured to close the first exhaust passage when a pressure on an upstream side from the fluid outlet of the discharge valve in the discharge passage is higher than a pressure in the first exhaust passage, and open the first exhaust passage when the pressure on the upstream side from the fluid outlet of the discharge valve in the discharge passage is not higher than the pressure in the first exhaust passage; and a control device configured to control an operation of the motor, wherein the control device is configured to control a rotational speed of the motor and regulate a pressure of the fluid discharged from the fluid discharge port, characterized in that the pressure regulating apparatus further comprises: a third exhaust port that is open to the outside of the diaphragm pump; and a third exhaust passage configured to make the third exhaust port communicate with an area on the upstream side from the fluid outlet of the discharge valve in the discharge passage. a diaphragm including a cup-shaped pump portion; a pump chamber including a wall including the pump portion; a driving device connected to a bottom of the pump portion and configured to convert a rotation into a reciprocating motion and increase/decrease a capacity of the pump chamber; a motor configured to apply a rotational force to the driving device; a fluid inlet, a fluid discharge port, and a first exhaust port that are open to outside of the diaphragm pump; a suction passage configured to make the pump chamber communicate with the fluid inlet; a suction valve configured to open/close the suction passage to make a fluid flow from the fluid inlet toward the pump chamber in a process in which the capacity of the pump chamber increases; a discharge passage configured to make the pump chamber communicate with the fluid discharge port; a discharge valve configured to open/close the discharge passage to make the fluid flow from the pump chamber toward the fluid discharge port in a process in which the capacity of the pump chamber decreases; a first exhaust passage configured to make the first exhaust port communicate with an area in the discharge passage between a fluid outlet of the discharge valve and the fluid discharge port; a differential pressure regulating valve configured to close the first exhaust passage when a pressure on an upstream side from the fluid outlet of the discharge valve in the discharge passage is higher than a pressure in the first exhaust passage, and open the first exhaust passage when the pressure on the upstream side from the fluid outlet of the discharge valve in the discharge passage is not higher than the pressure in the first exhaust passage; and a control device configured to control an operation of the motor, wherein the control device is configured to control a rotational speed of the motor and regulate a pressure of the fluid discharged from the fluid discharge port, characterized in that the pressure regulating apparatus further comprises: a third exhaust port that is open to the outside of the diaphragm pump; and a third exhaust passage configured to make the third exhaust port communicate with an area on the upstream side from the fluid outlet of the discharge valve in the discharge passage. a third exhaust port that is open to the outside of the diaphragm pump; and a third exhaust passage configured to make the third exhaust port communicate with an area on the upstream side from the fluid outlet of the discharge valve in the discharge passage.