To provide a fuel injection device capable of accurately controlling a combustion ratio in response to an engine speed and a load by changing a valve closing force in response to the engine speed and/or the load.

A valve closing force changing means 6 for changing the valve closing force of an elastic body 24 is provided at an injection means 4 having the elastic body 24 for giving the valve closing force against fuel pressure to switch a position from an injection position, in which fuel is injected, to a non-injection position, in which the fuel is not injected, in response to increased fuel pressure. When at least either detection value of an engine speed detecting means and a load detecting means exceeds the predetermined value, a valve closing force control means 5 controls the valve closing force changing means 6 to increase the valve closing force.