An apparatus for adjusting a height and an angle of a footrest support for a construction machine is disclosed, which can adjust the height and the angle of the footrest support, on which an operator puts his/her foot, in accordance with physical conditions of the operator. The apparatus includes pedal plates, a pedal arm having one end fixed to a second bracket and the other end having a through-hole for adjustment of a height of the pedal plate, a fixing plate installed in a predetermined position of the pedal arm, a fixing pin coupled to the through-hole of the fixing plate and a fastening plate installed in predetermined positions of left and right sides in a cabin and having fastening holes for adjustment of the height of the pedal plate formed thereon at equal intervals in upward and downward directions.
