To prevent water contained in high temperature water-emulsion fuel from vaporizing when a fuel supply pump which supplies water-emulsion fuel to a diesel engine can not be driven, by driving an anti-flush pump and keeping the pressure of the high temperature water-emulsion fuel inside a circulation line high.

Disclosed is a fuel supply device 11 with an anti-flash device which circulates a water-emulsion fuel obtained by blending a first fuel oil and water through a circulation line 15, thereby being capable of supplying a diesel engine 16 connected to the circulation line 15 with the water-emulsion fuel circulated through the circulation line 15. An anti-flash pump P2 is connected to the circulation line 15 to back up a fuel supply pump P1 for supplying a mixer 14 with the first fuel oil, the fuel supply pump P1 being driven by a first electric motor M1 and the anti-flash pump P2 being driven by a second pneumatic motor M2.