Device for controlling the supply of a gas, the device comprising: - an inlet that can be connected to a source of a gas that has a predetermined inlet pressure and an outlet for supplying said gas at an outlet pressure, it being possible to connect said outlet to an appliance; - a main body in which a regulating chamber that communicates with said inlet and said outlet is defined; - a pressure regulation membrane arranged in said chamber and a resilient opposition member that is associated with said membrane and generates an opposing force on said membrane when said gas in said chamber compresses said membrane; - a device for opening/closing said inlet; - a unit for manually actuating said device, which unit can move with respect to a main axis, said actuation unit comprising an activation element that can be actuated manually by a user, said activation element being designed to be actuated by at least one translation movement along said main axis and by at least one rotational movement about said main axis; - an actuation shaft which is rigidly connected to the membrane and can move by means of the translation of said activation element, said shaft being designed to interact with a portion for obstructing the supply outlet in order to open and/or close said supply outlet; wherein said actuation unit is operatively connected to said opening/closing device in order to open/close said inlet and in that said actuation unit is also operatively connected to said resilient opposition member and comprises a regulating device for regulating said resilient opposition member, which regulating device varies said opposing force, said regulating device comprising a cam element positioned in contact with said resilient opposition member, said cam element being moved by said activation element during said at least one rotational movement, and wherein said opening/closing device comprises a first element which comprises an opposing portion that defines a thrust element rigidly connected to the activation element, said opening/closing device comprising an indexer disc connected to the main body and comprising a reference opening through which the thrust element can pass when the first element is positioned, by means of rotation of the activation element, in a predetermined angular position about said main axis, characterized in that the opposing portion and the reference opening are designed such that: during an opening action, the activation element can be actuated by a translation movement in a first direction along the main axis, bringing the device from a second operative position, in which the thrust element is not in contact with the cam element and the first element is not in contact with the shaft, to a third operative position in which the first element is in contact with the shaft so as to move the shaft and the obstructing portion of the inlet in order to supply gas through said supply outlet at a predetermined outlet pressure; during a regulating action, the first element can move by the rotational movement about said main axis from the third operative position to a fourth operative position, during which rotational movement the thrust element abuts the cam element to cause it to translate, so as to vary the opposing force and the outlet pressure in relation to the predetermined outlet pressure. - an inlet that can be connected to a source of a gas that has a predetermined inlet pressure and an outlet for supplying said gas at an outlet pressure, it being possible to connect said outlet to an appliance; - a main body in which a regulating chamber that communicates with said inlet and said outlet is defined; - a pressure regulation membrane arranged in said chamber and a resilient opposition member that is associated with said membrane and generates an opposing force on said membrane when said gas in said chamber compresses said membrane; - a device for opening/closing said inlet; - a unit for manually actuating said device, which unit can move with respect to a main axis, said actuation unit comprising an activation element that can be actuated manually by a user, said activation element being designed to be actuated by at least one translation movement along said main axis and by at least one rotational movement about said main axis; - an actuation shaft which is rigidly connected to the membrane and can move by means of the translation of said activation element, said shaft being designed to interact with a portion for obstructing the supply outlet in order to open and/or close said supply outlet; during an opening action, the activation element can be actuated by a translation movement in a first direction along the main axis, bringing the device from a second operative position, in which the thrust element is not in contact with the cam element and the first element is not in contact with the shaft, to a third operative position in which the first element is in contact with the shaft so as to move the shaft and the obstructing portion of the inlet in order to supply gas through said supply outlet at a predetermined outlet pressure; during a regulating action, the first element can move by the rotational movement about said main axis from the third operative position to a fourth operative position, during which rotational movement the thrust element abuts the cam element to cause it to translate, so as to vary the opposing force and the outlet pressure in relation to the predetermined outlet pressure.