PURPOSE: To obtain the polymer excellent as a polymer for a resist material having a high resolution and suitable for a polymer blend by subjecting 3- methyl-4-t-butoxystyrene to living anionic polymn. and separating the t-butoxy groups from the resulting polymer.

CONSTITUTION: 3-Methyl-4-t-butoxystyrene of formula I is subjected to living anionic polymn. pref. using an organometallic compd. such as n-butyllithium as a polymn. initiator pref. in an org. solvent such as tetrahydrofuran. The resulting polymer, poly(3-methyl-4-t-butoxystyrene), is dissolved in a solvent such as acetone to give a soln., to which an acid such as hydrochloric acid is added dropwise to separate the t-butoxy groups from the polymer, giving a monodisperse poly(3-methyl-4-hydroxystyrene) having repeating units of formula II.