Disclosed is an apparatus for automatically adjusting clearance of a support yoke of a rack and pinion type steering apparatus, the apparatus including: a support yoke making contact with one side of a rack bar so as to support the rack bar; at least one cam assembled with one side of the support yoke so as to support the support yoke; a yoke plug which is positioned at one side of the cam so as to support the cam and is assembled with a rack housing; and a yoke spring included at one side of the support yoke so as to apply elastic force to the support yoke in a direction of the rack bar. In a case where the support yoke is worn away due to friction, etc. against the rack bar, while the cam performs relative rotation movement respective to the support yoke by means of an elastic force of the elastic member disposed between the support yoke and the cam, the spacing member pushes the support yoke in a direction of the rack bar so as to maintain a predetermined interval between the spacing member and the support yoke, thereby maintaining clearance of the support yoke in a predetermined degree.