A new photochromic compound of tetraazaporphyrin magnesium(II) appended with eight ferrocene units by ethynyl TPF was synthesized. Its photochromic properties and electrochemical properties were studied. As its redox potential was reversibly changed accompanying the open- and closed-ring photoisomerization of TPF with UV-vis light irradiation, TPF may be used as electrochemical switch controlled by light.