A hydrogen generator comprising: a reformer for generating a hydrogen-containing gas through a reforming reaction of a raw material gas and water; a raw material supply unit for supplying the raw material gas; a raw material flow measuring unit for measuring a flow of the raw material gas; a water supply unit for supplying the water; a first temperature detector for detecting a temperature of the reformer ; a combustor for combusting at least one of the raw material gas and the hydrogen-containing gas which are combustible gases by using air to heat the reformer ; a combustion air supply unit for supplying the air; and a control unit ; wherein the control unit is configured to control an amount of the raw material gas supplied from the raw material supply unit such that a first detection temperature detected by the first temperature detector reaches a predetermined temperature, and to control at least one of an amount of the water supplied from the water supply unit and an amount of the air supplied from the combustion air supply unit , based on the flow of the raw material gas which is measured by the raw material flow measuring unit , during control of the amount of the raw material gas, the hydrogen generator further includes a storage section for storing a measurement flow of the raw material gas during an operation of the hydrogen generator; characterized in that the control unit is configured to set a reference flow of the raw material gas based on the measurement flow of the raw material gas stored in the storage section , and to control at least one of a supply amount of the water and a supply amount of the air based on a result of comparison between the measurement flow of the raw material gas and the reference flow. a reformer for generating a hydrogen-containing gas through a reforming reaction of a raw material gas and water; a raw material supply unit for supplying the raw material gas; a raw material flow measuring unit for measuring a flow of the raw material gas; a water supply unit for supplying the water; a first temperature detector for detecting a temperature of the reformer ; a combustor for combusting at least one of the raw material gas and the hydrogen-containing gas which are combustible gases by using air to heat the reformer ; a combustion air supply unit for supplying the air; and a control unit ; wherein the control unit is configured to control an amount of the raw material gas supplied from the raw material supply unit such that a first detection temperature detected by the first temperature detector reaches a predetermined temperature, and to control at least one of an amount of the water supplied from the water supply unit and an amount of the air supplied from the combustion air supply unit , based on the flow of the raw material gas which is measured by the raw material flow measuring unit , during control of the amount of the raw material gas, the hydrogen generator further includes a storage section for storing a measurement flow of the raw material gas during an operation of the hydrogen generator; characterized in that the control unit is configured to set a reference flow of the raw material gas based on the measurement flow of the raw material gas stored in the storage section , and to control at least one of a supply amount of the water and a supply amount of the air based on a result of comparison between the measurement flow of the raw material gas and the reference flow. <EOS>