A fuel supply device has a main line, a fuel pump, a first return line, a second return line, a valve mechanism, a first pressure regulator, and a second pressure regulator. The fuel pump pressurizes the fuel in the fuel tank and supplies the fuel to a fuel distribution pipe via the main line. The first return line returns the fuel from the fuel distribution pipe to the fuel tank. The second return line is branched from the main line and returns the fuel from the main line to the fuel tank. The valve mechanism selectively connects and disconnects the second return line with respect to the main line. The first pressure regulator is arranged in the first return line. The second pressure regulator is provided in the second return line and adjusts fuel pressure to a lower level than the first pressure regulator does.