A diarylethene dimer connected with a diyne 1 (O-O) was synthesized. Upon irradiation with 350-nm light the colorless hexane solution of 1 (O-O) changed to a dark-blue solution, in which absorption maximum was observed at 574nm. The color is due to the formation of the isomer having one closed-ring form 1 (O-C). 1 (O-C) emitted red fluorescence at 720 nm and the intensity reversibly changed along with the photochromic reaction.