A method for preparing a cyclic olefin polymer is described. The method includes polymerizing cyclic olefin monomers or a cyclic olefin monomer with ethylene to prepare a cyclic olefin polymer solution; slowly adding a non-solvent drop wise to the cyclic olefin polymer solution to precipitate a cyclic olefin polymer; and filtering and drying the precipitated cyclic olefin polymer. In addition, the cyclic olefin polymer prepared using this method is described. According to the present invention, a spherical cyclic olefin polymer having a high bulk density can be easily separated from the cyclic olefin polymer solution by precipitation.