To prevent fuel injection finishing timing from being set within a range where a fuel injection rate is easily changed, in a fuel injection controller for a diesel engine, equipped with an injector which realizes a multistage opening according to fuel pressure.

In this fuel injection controller for a diesel engine, an injector is arranged which realizes a lift quantity LO in a range where fuel pressure supplied from a fuel injection pump is small, and realizes a lift quantity HO in a range where the fuel pressure is large in comparison with a predetermined pressure. When the rotational angle of the diesel engine reaches a predetermined rotational angle, fuel is supplied from the fuel injection pump toward the injector so as to start fuel injection, and fuel injection is finished. Therefore, fuel supply is stopped at a point of time when a desired fuel is ejected. Fuel injection finishing timing is prohibited to be set in timing that the opening of the injector is easily changed, that is, in timing that a fuel injection rate dQ/dt is easily changed.