Fuel injector

The device (1) has a piezoelectric, electrostrictive or magnetostrictive actuator (2) and a valve needle (12) that interacts with the actuator and a spring element (3) and has a valve closure body (13) that interacts with a valve seat surface (14). The actuator is at least partly radially enclosed over at least part of its axial length by at least one spring element whose force action moves the valve needle against the actuator's lift direction.