Disclosed herein are a phenyl-modified hybrid prepolymer, a phenyl-modified polydimethylsiloxane-based hybrid prepolymer, and a phenyl-modified polydimethylsiloxane-based hybrid polymer capable of controlling material hardness or surface tackiness depending on the intended use or purpose. A phenyl-modified hybrid prepolymer (B) is prepared by subjecting polydimethylsiloxane having trialkoxysilyl groups at both ends, phenyltrialkoxysilane, and diphenyldialkoxysilane to hydrolysis and condensation reaction. A phenyl-modified polydimethylsiloxane-based hybrid prepolymer (C) comprises (B), and is preferably prepared by mixing (B) and a phenyl-modified hybrid prepolymer (A) prepared by condensation reaction between polydimethylsiloxane having silanol groups at both ends and phenyltrialkoxysilane. The phenyl-modified polydimethylsiloxane-based hybrid polymer is obtained by heating and solidifying (C).