The nonresonant two-photon absorption spectrum of poly(dihexylsilylene) (1) in 3-methylpentane solution showed an abrupt thermochromism with a similar transition temperature to the one-photon absorption spectrum of 1. The parallel temperature dependence between the one-photon and two-photon absorption spectra suggests that the two-photon excited state involves an important contribution of the sigma-sigma* excited electronic configurations.