To provide a cycloolefin polymer which exhibits little reduction of light transmittance due to white turbidity or the like even when the accumulated irradiance level of a blue laser beam is increased at a wavelength of around 400 nm, a method producing such a cycloolefin polymer, and an optical component for a blue laser device.

The cycloolefin polymer is obtained by performing the addition polymerization of a cycloolefin (A) and a 2-20C α-olefin (B) using a metallocene catalyst or the like, adding a metal simple substance carried by a carrier so that the concentration of the metal simple substance ranges from 0.5 to 10% by weight relative to the addition polymer, and then causing the resultant product to come into contact with hydrogen at a temperature ranging from 150 to 200°C and hydrogen partial pressure ranging from 0.1 to 100 kgf/cm2. The resultant cycloolefin polymer is characterized in that a percentage ((UV peak area)/(RI peak area)×100) is 2.5 or less, where the peak area (UV peak area) is detected using a UV spectrum detector with a wavelength of 210 nm and the peak area (RI peak area) is detected using differential refractometer in GPC analysis. The cycloolefin polymer is molded into an optical component for a blue laser device.