A continuously variable valve duration apparatus may include a camshaft, a plurality of first cams and second cams of which a cam key is formed respectively thereto, and of which relative phase angles with respect to the camshaft are variable, a plurality of rotation rings mounted to the camshaft and of which a ring key is formed thereto respectively, a plurality of inner brackets transmitting rotation of the camshaft to the cam keys of the first cams and the seconds respectively, a plurality of slider housings of which each inner bracket is rotatable inserted therein, a support bracket connecting the slider housings and a control portion selectively moving the support bracket and moving positions of the slider housings so as to change rotation centers of the inner brackets.