<p>A pitch-controlling agent applicable to the process of production of pulps or papers, which can satisfactorily inhibit the adhesion of pitch to production units or products. The agent contains a polymer which has a weight-average molecular weight of 5,000 to 1,000,000 and which comprises (A) 20 to 95 % by mole of structural units derived from N-vinyl-2-pyrrolidone and (B) 5 to 80 % by mole of structural units derived from a cationic monomer such as an acrylate or methacrylate monomer.</p>
