A novel resin is provided which is renewable with less energy. A process for renewing the resin is also provided. The present invention includes a polymer having the repeating unit represented by Structural Formula (1) below, and a process for producing the polymer: [--P.sub.1--R--].sub.n (1). In the formula, P.sub.1 indicates an addition polymer moiety having a continuous hydrocarbon chain as the skeleton containing no condensation system, and is a polymer or oligomer prepared by addition polymerization of one or more monomers having a double bond; R indicates a linking group constituted of a condensation system for linking the polymer moieties P; and n is a number of repeating units and is an integer of 2 or more.