Reversible TiNi (= RTiNi) alloy thin film actuator has many advantages for micro sized robot. That is. a micro arm could be fabricated easily on silicon wafer because RTiNi alloy thin film has 3 functions. 1) a frame of the arm, 2) a joint of the arm and 3) an actuator of the arm. and moreover, this film could actuates the arm without friction. A micron sized flexible arm using RTiNi alloy thin film was designed on silicon wafer. IC process for fabricating this arm on silicon wafer was designed. The fabricating process for this arm and its heat treatment process for the RTiNi are presented.