Patent ID: 7781107

Claim:
A fuel cell system comprising: a fuel cell; a gas supply pipe that supplies gas used for generating electricity to the fuel cell; a gas discharge pipe that discharges gas discharged from the fuel cell, a gas-liquid separator located in at least part of the gas discharge pipe and the gas supply pipe, for collecting water in the discharged gas; and a freezing judgment device that performs a freezing judgment of the water collected within the gas-liquid separator based on differences in volume of the water collected within the gas-liquid separator when frozen and when not frozen, wherein a detecting section of the freezing judgment device is provided in the gas-liquid separator the freezing judgment device comprises an elastic member that changes shape with pressure and is provided at any part under the water surface within the gas-liquid separator, wherein the freezing judgment device performs the freezing judgment based on a shape change state of the elastic member and wherein the freezing judgment is performed during activation of the fuel cell system, and the fuel cell system comprises a system activation prohibition module that prohibits activation of the fuel cell system when freezing of the water is detected.