A hydrogen generation apparatus, comprising: a reformer (2, 31) that generates a hydrogen-containing gas from a hydrocarbon-containing raw material gas through a reforming reaction; a raw material gas supply device (3, 34) that supplies the raw material gas to the reformer; a combustor (4, 35) that combusts at least one of the raw material gas and the hydrogen-containing gas which pass through the reformer, or any off-gas that includes the hydrogen-containing gas, which is not used, to heat the reformer; a combustion air supply device (9, 36) that supplies combustion air to the combustor; a raw material gas supply amount detector (5, 37) that detects the amount of the raw material gas supplied to the reformer; a reforming temperature detector (6, 38) that detects a temperature of the reformer; and a controller (7, 39) that performs control in accordance with a control parameter; characterized in that the controller (7, 39) is configured to set the control parameter on the basis of a reforming temperature, which is detected by the reforming temperature detector, in a case where the raw material gas supply device supplies the raw material gas so that the amount of the raw material gas supplied, which is detected by the raw material gas supply amount detector, becomes a predetermined value, or on the basis of a temperature variation rate, which is detected by the reforming temperature detector, when the temperature of the reformer rises due to heating by the combustor, the controller (7, 39) is configured to select an optimal control parameter among at least two kinds of the control parameters depending on compositions of at least two kinds of the raw material gases, which are different in the amount of heat, on the basis of the reforming temperature or the temperature variation rate, the controller (7, 39) is configured to perform control on the basis of a first control parameter that is one kind of the control parameter, and the controller (7, 39) is configured to perform control after changing to a second control parameter, which is a different kind of the control parameter, in a case where the reforming temperature deviates from a predetermined threshold value or in a case where the temperature variation rate deviates from a predetermined threshold value. a reformer (2, 31) that generates a hydrogen-containing gas from a hydrocarbon-containing raw material gas through a reforming reaction; a raw material gas supply device (3, 34) that supplies the raw material gas to the reformer; a combustor (4, 35) that combusts at least one of the raw material gas and the hydrogen-containing gas which pass through the reformer, or any off-gas that includes the hydrogen-containing gas, which is not used, to heat the reformer; a combustion air supply device (9, 36) that supplies combustion air to the combustor; a raw material gas supply amount detector (5, 37) that detects the amount of the raw material gas supplied to the reformer; a reforming temperature detector (6, 38) that detects a temperature of the reformer; and a controller (7, 39) that performs control in accordance with a control parameter; characterized in that the controller (7, 39) is configured to set the control parameter on the basis of a reforming temperature, which is detected by the reforming temperature detector, in a case where the raw material gas supply device supplies the raw material gas so that the amount of the raw material gas supplied, which is detected by the raw material gas supply amount detector, becomes a predetermined value, or on the basis of a temperature variation rate, which is detected by the reforming temperature detector, when the temperature of the reformer rises due to heating by the combustor, the controller (7, 39) is configured to select an optimal control parameter among at least two kinds of the control parameters depending on compositions of at least two kinds of the raw material gases, which are different in the amount of heat, on the basis of the reforming temperature or the temperature variation rate, the controller (7, 39) is configured to perform control on the basis of a first control parameter that is one kind of the control parameter, and the controller (7, 39) is configured to perform control after changing to a second control parameter, which is a different kind of the control parameter, in a case where the reforming temperature deviates from a predetermined threshold value or in a case where the temperature variation rate deviates from a predetermined threshold value.