A prestroke control device for a fuel injection pump includes at least one control sleeve slidably fitted on at least one plunger, a control rod engaging the control sleeve, the control rod extending perpendicularly to the plunger and rotatable about an axis thereof for varying an axial position of the control sleeve relative to the plunger to thereby control the prestroke of the plunger, and an actuator for rotatively driving the control rod about its own axis. A counterweight is movable in unison with rotation of the control rod for cancelling a rotating force generated by axial movement of the control sleeve and acting upon the control rod.