To provide a method for setting an amount of fuel fed to an internal combustion engine capable of automatically maintaining a current running state corresponding to a change in running load substantially in a steady state without needing special operation by a driver.

A CPU in an ECU 40 decides that the operation state of a diesel engine 1 is approximately in a steady state when a change mount of an accelerator opening ACCP and an engine rotation speed NE is below a predetermined value and held for a predetermined time or more. In the approximate steady state, a CPU calculates a difference between an engine rotating speed NE in completion of conditions (a condition completion rotating speed) and a present engine rotating speed NE (a real rotating speed). The CPU determines a correction factor based on the real rotating speed and calculates a correction amount of an injection amount by multiplying the difference by the correction factor. The CPU corrects the fuel injection amount by adding the correction amount to the basic fuel injection amount determined by the acceleration opening ACCP and engine rotation speed NE.