An operation control device for a fuel cell power plant, which controls a generated power of a fuel cell stack that performs power generation using hydrogen on the basis of a target generated power, comprising: an anode gas supply mechanism that supplies an anode gas containing hydrogen to the fuel cell stack; a sensor that detects a power generation condition of the fuel cell stack by measuring a load current, a stack voltage and / or a hydrogen concentration of the anode gas in the fuel cell stack; and a programmable controller programmed to: control the anode gas supply mechanism to cause an anode gas pressure pulsation in which an anode gas pressure in the fuel cell stack pulsates between an upper limit pressure (Pamax, Pmax) and a lower limit pressure (Pamin, Pmin); determine on the basis of the power generation condition of the fuel cell stack by comparing the output of the sensor with a predetermined value whether or not a hydrogen supply amount supplied to the fuel cell stack satisfies an amount required to generate the target generated power, control the anode gas supply mechanism to cause the anode gas pressure pulsation in a normal mode when the hydrogen supply amount is sufficient, and control the anode gas supply mechanism to cause the anode gas pressure pulsation in a recovery mode when the hydrogen supply amount is insufficient; wherein the upper limit pressure (Pamax, Pmax) and the lower limit pressure (Pamin, Pmin) are set to be higher in the recovery mode than in the normal mode. an anode gas supply mechanism that supplies an anode gas containing hydrogen to the fuel cell stack; a sensor that detects a power generation condition of the fuel cell stack by measuring a load current, a stack voltage and / or a hydrogen concentration of the anode gas in the fuel cell stack; and a programmable controller programmed to: control the anode gas supply mechanism to cause an anode gas pressure pulsation in which an anode gas pressure in the fuel cell stack pulsates between an upper limit pressure (Pamax, Pmax) and a lower limit pressure (Pamin, Pmin); determine on the basis of the power generation condition of the fuel cell stack by comparing the output of the sensor with a predetermined value whether or not a hydrogen supply amount supplied to the fuel cell stack satisfies an amount required to generate the target generated power, control the anode gas supply mechanism to cause the anode gas pressure pulsation in a normal mode when the hydrogen supply amount is sufficient, and control the anode gas supply mechanism to cause the anode gas pressure pulsation in a recovery mode when the hydrogen supply amount is insufficient; wherein the upper limit pressure (Pamax, Pmax) and the lower limit pressure (Pamin, Pmin) are set to be higher in the recovery mode than in the normal mode. control the anode gas supply mechanism to cause an anode gas pressure pulsation in which an anode gas pressure in the fuel cell stack pulsates between an upper limit pressure (Pamax, Pmax) and a lower limit pressure (Pamin, Pmin); determine on the basis of the power generation condition of the fuel cell stack by comparing the output of the sensor with a predetermined value whether or not a hydrogen supply amount supplied to the fuel cell stack satisfies an amount required to generate the target generated power, control the anode gas supply mechanism to cause the anode gas pressure pulsation in a normal mode when the hydrogen supply amount is sufficient, and control the anode gas supply mechanism to cause the anode gas pressure pulsation in a recovery mode when the hydrogen supply amount is insufficient; wherein the upper limit pressure (Pamax, Pmax) and the lower limit pressure (Pamin, Pmin) are set to be higher in the recovery mode than in the normal mode.