An active vibration damper including: an inner shaft member provided to a movable member; an outer tube member provided to a stator; a pair of leaf springs elastically connecting axially both sides of the inner shaft member and the outer tube member so as to make a linear actuator operatable by itself; an elastic connecting rubber connecting the inner shaft member and the outer tube member; a mass body holding portion provided to the inner shaft member for holding an additional mass body that is disposed further outwardly than the elastic connecting rubber; and a housing having a structure dividable in an axial direction in which respective openings are secured to each other with an annular seal being interposed therebetween at an outer peripheral side of the elastic connecting rubber.