Provided is a fuel supply device for an internal combustion engine. When fuel pressure in a high-pressure fuel pipe changes as a result of the driving of a high-pressure pump, the changing fuel pressure propagates as pulsation into a low-pressure fuel pipe. A degree of influence of propagation of pulsation decreases as fuel pressure in the low-pressure fuel pipe increases. When the high-pressure pump is in an operating state where the degree of influence of the pulsation of the fuel pressure propagating from the high-pressure fuel pipe on the fuel pressure in the low-pressure fuel pipe is high, boost control for driving a feed pump to raise the fuel pressure in the low-pressure fuel pipe is executed.