To miniaturize the outer shape of a vaporizer including a primary and a secondary regulator.

In a fuel supply device (vaporizer 1) including the primary regulator 8 and the secondary regulator 9, each diaphragm 14, 23 is provided in a laminated condition so as to overlap a part of the diaphragm, each axial line of the diaphragm is mutually biases, and a center of a communication port valve seat 22 including a communication port having liquefied gas fuel pass from the primary regulator to the secondary regulator is arranged at the overlap part of the diaphragm. Length (width) of the vaporizer in a direction connecting each axial line of the diaphragm can be shortened. Since pressure adjusting work can be easily done from one direction by providing each pressure adjusting part screw 18, 28 on a same surface of the vaporizer, pressure can be accurately adjusted. Since screws relatively long in axial directions are arranged on same surface side when pressure adjusting screws are used, lamination direction thickness of the vaporized can be thinned.