To provide a warming-up system in which a period of time taken to warm up a fuel cell is shorter than that for conventional ones. A warming-up system according to an embodiment includes a fuel cell, a motor, a rotation shaft, a speed reducer, a measuring unit, and a control unit. The motor convert electrical power generated by the fuel cell into a rotative force. The speed reducer brake the rotation shaft that is rotating. The measuring unit measure a temperature of the fuel cell. The control unit is configured to determine whether to perform warming up for the fuel cell, based on the temperature. When the control unit determines to perform the warming up, the control unit causes the motor and the speed reducer to operate, and uses heat generated in the fuel cell and heat generated in the speed reducer to warm up the fuel cell.