An electromagnetic fuel injector for internal combustion engines has a core defining therein a central bore and a fuel adjuster disposed therein and having an upstream end spaced downstream from an inlet end of the core. The central bore includes an inlet portion extending between the inlet end of the core and the upstream end of the fuel adjuster and providing an inner peripheral surface operative to guide the fuel in a laminar flow toward and into the fuel adjuster for thereby minimizing the occurrence of pulsated fuel pressure variation and voids which took place heretofore to cause cavitation in the fuel passage in the injector, whereby the range of fuel injection control can be widened.