A fuel cell system is configured to generate power by supplying anode gas and cathode gas to a fuel cell. The fuel cell system includes a load connected to the fuel cell and an IV estimation unit configured to change an output current of the fuel cell with a predetermined width by adjusting power supplied to the load during the warm-up of the fuel cell. The fuel cell system is configured to estimate an IV characteristic of the fuel cell on the basis of at least two sets of an output current value and an output voltage value detected while the output current is changed. The fuel cell system includes an IV estimation stop unit configured to stop the execution of the IV estimation on the basis of an output of the fuel cell during the execution of the IV estimation.