A mixing tank for a fuel cell is provided with a container housing fuel for the fuel cell, an absorbent member housed in the container, which has a cavity therein, an inlet flow path interconnecting the fuel cell and the container so as to conduct an exhaust from the fuel cell to the container and admix the exhaust with the fuel to form a mixture absorbed in the absorbent member, an exhaust flow path interconnecting the cavity and an outside of the mixing tank so as to conduct gas to the outside and an outlet flow path interconnecting the absorbent member and the fuel cell so as to conduct the mixture absorbed in the absorbent member to the fuel cell.