Disclosed is a fuel supplying device of an internal combustion engine, comprising a low-pressure circuit, a high-pressure pump coupled to the low-pressure circuit and conveys fuel into a fuel reservoir, a volume flow control valve assigned to the high-pressure pump, an electromechanical pressure regulator connected to the fuel reservoir and the low-pressure circuit and can direct fuel from the fuel reservoir into the low-pressure circuit, a regulating mechanism which generates an actuation signal for the volume flow control valve by a first controller in a first mode which generating an actuation signal for the electromechanical pressure regulator with the aid of a second controller in a second mode. The mode of the fuel supplying mechanism is switched in accordance with a fuel pressure error value resulting from a detected fuel pressure and a predefined fuel pressure. The mode can additionally be switched according to the throughput of the high-pressure pump.