A fuel injector configured and arranged to inject fuel into a combustion chamber comprises a casing member, a fuel discharge valve and a micro nozzle. The casing member includes a hydraulic chamber configured to contain pressurized fuel and a flow rate regulating hole arranged to discharge the fuel from inside the hydraulic chamber. The fuel discharge valve is configured and arranged to open and close the flow rate regulating hole. The micro nozzle is disposed in a downstream part with respect to the fuel discharge valve, and has at least one through hole arranged to inject the fuel discharged from the flow rate regulating hole into the combustion chamber. The micro nozzle further includes a heating structure configured and arranged to selectively emit heat to raise temperature of the fuel that passes through the at least one through hole of the micro nozzle upon activation of the heating structure.