We examined the solvent effect on the electronic absorption and infrared absorption spectra of a push-pull molecule fabricated by connecting donor and acceptor segments linked with a quinoid bridge, {4-[4,5-bis(methylsulfanyl)-1,3-dithiol-2-ylidene]cyclohexa-2,5-dien-1-ylidene}malononitrile (BMDCM), in liquid solutions. A BMDCM molecule represented by a resonance hybrid of the two canonical structures, the quinoid and benzenoid forms, showed remarkable solvatochromism. By analyzing the vibrational progressions in the electronic absorption spectra, we have grasped the behaviors of molecular structure and intramolecular charge distribution for the ground and excited states in reference to the solvent polarity.