Abstract: A fuel supply device is provided capable of supplying a necessary amount of fuel while ensuring predetermined stoichiometric characteristics over a wide range of flow rates. The body unit of the fuel supply device includes the first ejector, the second ejector, and a switching valve. The switching valve has a function to select either one of a first passage or a second passage for communicating with the valve chamber and to block the other passage. The first passage is communicated with a nozzle of the first ejector, and the second passage is communicated with a nozzle of the second ejector. The first ejector has a diffuser passage communicated with the reflux chamber, the second ejector has a diffuser passage communicated with the reflux chamber, and the diffuser passage 43 and the diffuser passage are connected with a hydrogen outlet through a merging passage.