A fuel cell system comprising: a fuel cell that includes an installation port and a discharge port for a reactant gas that is used for electric power generation; a first injection device configured to intermittently inject the reactant gas; a second injection device and a third injection device configured to continuously inject the reactant gas; an ejector that includes an ejection port from which the reactant gas discharged from the discharge port is ejected together with the reactant gas injected from the first injection device or the second injection device; a first flow passage that connects the installation port and the ejection port; a second flow passage through which the reactant gas injected from the third injection device is led to the first flow passage without the ejector; and a control device configured to control an injection of the first injection device, the second injection device and the third injection device, wherein: the ejector includes a common third flow passage through which the reactant gas discharged from the discharge port and the reactant gas injected from the first injection device and the second injection device flow to the ejection port; and the control device is configured to perform a warm-up operation of the fuel cell wherein the control device executes an injection of the third injection device, and executes an injection of the second injection device to restrain a reverse flow of the reactant gas, the reverse flow being a reverse flow by which the reactant gas flows from the third injection device to the third flow passage through the second flow passage, the first flow passage and the ejection port, and the control device is configured to execute the injection of the first injection device after completion of the warm-up operation of the fuel cell, wherein the first injection device includes an injector; and each of the second injection device and the third injection device includes a linear solenoid valve. a fuel cell that includes an installation port and a discharge port for a reactant gas that is used for electric power generation; a first injection device configured to intermittently inject the reactant gas; a second injection device and a third injection device configured to continuously inject the reactant gas; an ejector that includes an ejection port from which the reactant gas discharged from the discharge port is ejected together with the reactant gas injected from the first injection device or the second injection device; a first flow passage that connects the installation port and the ejection port; a second flow passage through which the reactant gas injected from the third injection device is led to the first flow passage without the ejector; and a control device configured to control an injection of the first injection device, the second injection device and the third injection device, wherein: the ejector includes a common third flow passage through which the reactant gas discharged from the discharge port and the reactant gas injected from the first injection device and the second injection device flow to the ejection port; and the control device is configured to perform a warm-up operation of the fuel cell wherein the control device executes an injection of the third injection device, and executes an injection of the second injection device to restrain a reverse flow of the reactant gas, the reverse flow being a reverse flow by which the reactant gas flows from the third injection device to the third flow passage through the second flow passage, the first flow passage and the ejection port, and the control device is configured to execute the injection of the first injection device after completion of the warm-up operation of the fuel cell, wherein the first injection device includes an injector; and each of the second injection device and the third injection device includes a linear solenoid valve. the ejector includes a common third flow passage through which the reactant gas discharged from the discharge port and the reactant gas injected from the first injection device and the second injection device flow to the ejection port; and the control device is configured to perform a warm-up operation of the fuel cell wherein the control device executes an injection of the third injection device, and executes an injection of the second injection device to restrain a reverse flow of the reactant gas, the reverse flow being a reverse flow by which the reactant gas flows from the third injection device to the third flow passage through the second flow passage, the first flow passage and the ejection port, and the control device is configured to execute the injection of the first injection device after completion of the warm-up operation of the fuel cell, wherein the first injection device includes an injector; and each of the second injection device and the third injection device includes a linear solenoid valve.