beta-Cyclodextrin (beta-CD) pseudopolyrotaxanes containing poly(thiophene-2,5-diyl), PTh, or poly(3-methylthiophene-2,5-diyl)s, P3MeThs, as an axle were prepared. Structures of the pseudopolyrotaxanes and their inclusion behavior with beta-CD were investigated. The UV-vis measurements revealed that inclusion of P3MeThs by beta-CD depended on the flexibility of the main chain and their molecular weight.