A device for controlling an amount of hot dip galvanization adhesion, the device comprises: a nozzle (22, 23) communicating with a gas supply device via a duct and configured to spray gas supplied from the gas supply device onto a steel plate to which molten metal adherers; characterized in that the device comprises: the duct branching in two directions and having one branched portion communicating with the nozzle (22, 23) and another branched portion being open; a first valve configured to control an actual gas pressure P1' of the nozzle (22, 23), said first valve being arranged in said one branched portion communicating with the nozzle (22, 23); a second valve configured to control a gas flow rate Q2 of the gas to be diffused from the other branched portion of the duct to an outside of a system, said second valve being arranged in said branched portion being open; a pressure setting unit configured to set a set gas pressure P1 of the nozzle (22, 23); a first valve opening degree setter configured to set a valve opening degree MV1 of the first valve, based on an instruction from a computation processing unit; a second valve opening degree setter configured to set a valve opening degree MV2 of the second valve, based on an instruction from the computation processing unit; the computation processing unit including means for obtaining the set gas pressure P1 from the pressure setting unit, said computation processing unit being configured to obtain the valve opening degree MV1 at which the gas pressure P1' becomes equal to the set gas pressure P1, and instruct the first valve opening degree setter about the obtained valve opening degree MV1, the computation processing unit configured to obtain the valve opening degree MV2 at which a total gas flow rate QT of the gas supplied from the gas supply device is constant, and instruct the second valve opening degree setter about the obtained valve opening degree MV2. a nozzle (22, 23) communicating with a gas supply device via a duct and configured to spray gas supplied from the gas supply device onto a steel plate to which molten metal adherers; characterized in that the device comprises: the duct branching in two directions and having one branched portion communicating with the nozzle (22, 23) and another branched portion being open; a first valve configured to control an actual gas pressure P1' of the nozzle (22, 23), said first valve being arranged in said one branched portion communicating with the nozzle (22, 23); a second valve configured to control a gas flow rate Q2 of the gas to be diffused from the other branched portion of the duct to an outside of a system, said second valve being arranged in said branched portion being open; a pressure setting unit configured to set a set gas pressure P1 of the nozzle (22, 23); a first valve opening degree setter configured to set a valve opening degree MV1 of the first valve, based on an instruction from a computation processing unit; a second valve opening degree setter configured to set a valve opening degree MV2 of the second valve, based on an instruction from the computation processing unit; the computation processing unit including means for obtaining the set gas pressure P1 from the pressure setting unit, said computation processing unit being configured to obtain the valve opening degree MV1 at which the gas pressure P1' becomes equal to the set gas pressure P1, and instruct the first valve opening degree setter about the obtained valve opening degree MV1, the computation processing unit configured to obtain the valve opening degree MV2 at which a total gas flow rate QT of the gas supplied from the gas supply device is constant, and instruct the second valve opening degree setter about the obtained valve opening degree MV2. the duct branching in two directions and having one branched portion communicating with the nozzle (22, 23) and another branched portion being open; a first valve configured to control an actual gas pressure P1' of the nozzle (22, 23), said first valve being arranged in said one branched portion communicating with the nozzle (22, 23); a second valve configured to control a gas flow rate Q2 of the gas to be diffused from the other branched portion of the duct to an outside of a system, said second valve being arranged in said branched portion being open; a pressure setting unit configured to set a set gas pressure P1 of the nozzle (22, 23); a first valve opening degree setter configured to set a valve opening degree MV1 of the first valve, based on an instruction from a computation processing unit; a second valve opening degree setter configured to set a valve opening degree MV2 of the second valve, based on an instruction from the computation processing unit; the computation processing unit including means for obtaining the set gas pressure P1 from the pressure setting unit, said computation processing unit being configured to obtain the valve opening degree MV1 at which the gas pressure P1' becomes equal to the set gas pressure P1, and instruct the first valve opening degree setter about the obtained valve opening degree MV1, the computation processing unit configured to obtain the valve opening degree MV2 at which a total gas flow rate QT of the gas supplied from the gas supply device is constant, and instruct the second valve opening degree setter about the obtained valve opening degree MV2.