Novel photochromic bis(3-thienyl)ethene with a 2,5-disubstituted thienyl unit, which shows photoswitching of solvatochromic property, was synthesized. The open-ring isomer showed solvatochromic behavior, while the closed-rimy isomer did not. It was suggested that the alteration of the pi-conjugated bond structure is the main cause of the switching of the solvatochromic property.