A regulator for medicine infusion comprising: a housing having an inlet communicating with an inflow conduit which extends to communicate with a liquid medicine storage space, an outlet communicating with an outflow conduit, and an internal space communicating with the inlet and the outlet; a membrane member being located in the internal space of the housing and forming a medicine flow passage between the inlet and the outlet, the membrane member receiving a pressure of a liquid medicine discharged via the medicine flow passage from the inlet to the outlet and the shape of the membrane member being changed depending on a flow rate of the liquid medicine discharged via the medicine flow passage from the inlet to the outlet; a lever being located below the membrane member and having an inlet side extension portion and an outlet side extension portion opposed to each other with respect to a rotary axis, the inlet side extension portion in contact with a lower surface of the membrane member and rotating on the rotary axis, according to the flow rate the liquid medicine discharged via the medicine flow passage from the inlet to the outlet, to change the shape of the membrane member so on that the shape changed membrane member blocks or opens the inlet; and a resilient plate being located between the membrane member and the lever and being in close contact with both the membrane member and the lever, the resilience of the resilient plate being adjusted so as to allow the pressure of the liquid medicine received through the membrane member to be delivered to the outlet side extension portion of the lever only when the flow rate of the liquid medicine exceeds a predetermined flow rate needed for a patient. a housing having an inlet communicating with an inflow conduit which extends to communicate with a liquid medicine storage space, an outlet communicating with an outflow conduit, and an internal space communicating with the inlet and the outlet; a membrane member being located in the internal space of the housing and forming a medicine flow passage between the inlet and the outlet, the membrane member receiving a pressure of a liquid medicine discharged via the medicine flow passage from the inlet to the outlet and the shape of the membrane member being changed depending on a flow rate of the liquid medicine discharged via the medicine flow passage from the inlet to the outlet; a lever being located below the membrane member and having an inlet side extension portion and an outlet side extension portion opposed to each other with respect to a rotary axis, the inlet side extension portion in contact with a lower surface of the membrane member and rotating on the rotary axis, according to the flow rate the liquid medicine discharged via the medicine flow passage from the inlet to the outlet, to change the shape of the membrane member so on that the shape changed membrane member blocks or opens the inlet; and a resilient plate being located between the membrane member and the lever and being in close contact with both the membrane member and the lever, the resilience of the resilient plate being adjusted so as to allow the pressure of the liquid medicine received through the membrane member to be delivered to the outlet side extension portion of the lever only when the flow rate of the liquid medicine exceeds a predetermined flow rate needed for a patient.