A norbornene-based polymer, which is formed by addition polymerization of a composition comprising at least one norbornene derivative represented by formula (1): ##STR00001## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7 and R.sup.8 each independently represents a hydrogen atom or a substituent; and n represents an integer of 0 to 2.