A height adjusting apparatus for vehicle seats may include seat side frames provided on both side ends of a seat part of a seat, each of the seat side frames connected to the seat bracket via a front link and a rear link, the support rod coupling the seat side frames to each other, the pinion gear provided on a seat side frame, the rack gear link having on one end thereof a rack gear which engages with an upper end of the pinion gear, and coupled at the other end thereof to a hinge of the front link placed on the seat bracket, so that, when the pinion gear is driven, the rack gear link pulls the seat side frame forwards to lift it up, and the support pin provided on the seat side frame in such a way as to be placed above the rack gear.