A method of producing a hot-dip galvanized steel sheet using a continuous hot-dip galvanizing apparatus that includes: an annealing furnace in which a heating zone, a soaking zone, and a cooling zone are arranged in the stated order; and a hot-dip galvanizing line adjacent to the cooling zone, the method comprising: annealing a steel strip whose Si content is 0.2 mass% or more by conveying the steel strip through the heating zone, the soaking zone, and the cooling zone in the stated order inside the annealing furnace; and applying a hot-dip galvanized coating onto the steel strip discharged from the cooling zone, using the hot-dip galvanizing line, wherein reducing gas or non-oxidizing gas is supplied into the soaking zone, the reducing gas or the non-oxidizing gas including: humidified gas humidified by a humidifying device; and dry gas not humidified by the humidifying device, and while a width and a sheet passing speed of the steel strip passing through the soaking zone are constant, a variation of pressure in the annealing furnace is suppressed by adjusting a flow rate of the dry gas, and a variation range of an amount of moisture supplied into the soaking zone by the humidified gas is limited to 20 % or less, wherein a flow rate and a dew point of the humidified gas are set so that an amount of moisture M supplied into the soaking zone by the humidified gas and expressed in g/min satisfies the following Formula: 40 + Vf W − 0.9 S + 4 / 90 < M < 60 + Vf W − 0.9 S + 4 / 90 where Vf is a volume of the soaking zone expressed in m 3, W is the width of the steel strip passing through the soaking zone and expressed in m, and S is the sheet passing speed of the steel strip expressed in m/s, and wherein a dew point in the soaking zone measured at a dew point measurement port provided in the soaking zone is controlled to -25 °C or more and 0 °C or less, the dew point measurement port being provided in a region of upper 1/2 of the soaking zone in a height direction, and located 1 m or more away from a position of a supply port of the humidified gas provided in the soaking zone and 1 m or more away from an inner wall position of the soaking zone facing the supply port. annealing a steel strip whose Si content is 0.2 mass% or more by conveying the steel strip through the heating zone, the soaking zone, and the cooling zone in the stated order inside the annealing furnace; and applying a hot-dip galvanized coating onto the steel strip discharged from the cooling zone, using the hot-dip galvanizing line, wherein reducing gas or non-oxidizing gas is supplied into the soaking zone, the reducing gas or the non-oxidizing gas including: humidified gas humidified by a humidifying device; and dry gas not humidified by the humidifying device, and while a width and a sheet passing speed of the steel strip passing through the soaking zone are constant, a variation of pressure in the annealing furnace is suppressed by adjusting a flow rate of the dry gas, and a variation range of an amount of moisture supplied into the soaking zone by the humidified gas is limited to 20 % or less, wherein a flow rate and a dew point of the humidified gas are set so that an amount of moisture M supplied into the soaking zone by the humidified gas and expressed in g/min satisfies the following Formula: 40 + Vf W − 0.9 S + 4 / 90 < M < 60 + Vf W − 0.9 S + 4 / 90 where Vf is a volume of the soaking zone expressed in m 3, W is the width of the steel strip passing through the soaking zone and expressed in m, and S is the sheet passing speed of the steel strip expressed in m/s, and wherein a dew point in the soaking zone measured at a dew point measurement port provided in the soaking zone is controlled to -25 °C or more and 0 °C or less, the dew point measurement port being provided in a region of upper 1/2 of the soaking zone in a height direction, and located 1 m or more away from a position of a supply port of the humidified gas provided in the soaking zone and 1 m or more away from an inner wall position of the soaking zone facing the supply port. where Vf is a volume of the soaking zone expressed in m 3, W is the width of the steel strip passing through the soaking zone and expressed in m, and S is the sheet passing speed of the steel strip expressed in m/s, and wherein a dew point in the soaking zone measured at a dew point measurement port provided in the soaking zone is controlled to -25 °C or more and 0 °C or less, the dew point measurement port being provided in a region of upper 1/2 of the soaking zone in a height direction, and located 1 m or more away from a position of a supply port of the humidified gas provided in the soaking zone and 1 m or more away from an inner wall position of the soaking zone facing the supply port.