NOVELTY - Fuel tank for a fuel cell that is connectable to a fuel cell main unit having an anode and a cathode, comprises a casing; and a partition plate configured to move within the casing. The partition plate is configured to a partition interior of the casing into a fuel storage portion that stores a liquid fuel to be supplied to the anode and a fuel-pressurizing portion that is capable of storing emission derived from the cathode.    USE - For a fuel cell, and a fuel cell system (claimed) that is attached, e.g., to mobile equipments (e.g., portable telephones) and small-size, portable-use equipment (e.g., personal computers).    ADVANTAGE - The tank allows stable fuel supply to be performed, and performs the disposal of emission as well.    DETAILED DESCRIPTION - Fuel tank (100) for a fuel cell that is connectable to a fuel cell main unit having an anode and a cathode, comprises a casing (140); and a partition plate (130) configured to move within the casing. The partition plate is configured to a partition interior of the casing into a fuel storage portion (110) that stores a liquid fuel (111) to be supplied to the anode and a fuel-pressurizing portion (120) that is capable of storing emission derived from the cathode. It is further configured to move by a pressure increase in the fuel-pressurizing portion with the emission supplied to the fuel-pressurizing portion to pressurize the liquid fuel in the fuel storage portion, without moving the partition plate when the emission is not supplied to the fuel-pressurizing portion so as not to pressurize the liquid fuel. An INDEPENDENT CLAIM is also included for a fuel cell system, comprising a fuel cell main unit that has an anode and a cathode with an electrolyte membrane in between, that supplies a liquid fuel to the anode and that supplies an oxidizer made of gas to the cathode to perform power generation; and the above fuel tank.    DESCRIPTION OF DRAWING(S) - The figure shows a sectional view of a fuel tank.    Fuel tank (100)    Fuel storage portion (110)    Liquid fuel (111)    Fuel-pressurizing portion (120)    Partition plate (130)    Casing (140)    Casing inner wall (141)    Pressure-bleeding valve (150)