Interplay among multiple degrees of freedoms in electron-transfer-type spin-crossover systems has been investigated by using a multiprobe system evaluating dielectric, optical, and transport properties. Increase in conductivity associated with a change in optical spectrum is found at around the spin-crossover temperature between the low- and high-spin states in [Co((R)-pabn)] [Fe(Tp)(CN)(3)](BF4)center dot MeOH center dot 2H(2)O, where (R)-pabn: (R)-N2,N(2')-bis(pyridin-2-ylmethyl-1,1'-binaphthyl-2,2'-diamine and Tp: hydrotris(pyrazollyl)borate. In the dielectric constant, a very slow dielectric dispersion is found to grow in the high-spin state, showing that some macroscopic motion and/or fluctuation exist.