A fuel supply apparatus for an internal combustion engine includes a fuel pump, a fuel pipe, a reduction valve, and an electronic control unit. The electronic control unit is configured to drive the fuel pump to rotate such that a required flow rate of the fuel is realized, while adjusting the fuel pressure in the fuel pipe to a target value, by driving the fuel pump to rotate. The electronic control unit is configured to operate the reduction valve to be opened when the operation state of the fuel pump is a first operation state. The first operation state is the operation state of the fuel pump where the frequency of the fuel pump has a value within a resonance area.