Photochromic compound

A photochromic compound represented by the following general formula (II):

• ##STR327## wherein R.sub.1 and R.sub.2, which may be the same or different, represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a phenyl group, a benzyl group, a phenethyl group, an alkylamino group having 1 to 4 carbon atoms, or a dialkylamino group having 2 to 8 carbon atoms, ##STR328## represents a norbornylidene group or a bicyclo [3.3.1]9-nonylidene group which may be substituted with at least one member selected from the group consisting of a halogen atom, a cyano group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogenoalkyl group having 1 to 4 carbon atoms, a phenyl group, a benzyl group, and a dialkylamino group having 2 to 8 carbon atoms, a phenyl group, a benzyl group and a dialkylamino group having 2 to 8 carbon atoms;
• ##STR329## represents a divalent unsaturated heterocyclic group selected from the group consisting of a pyridine ring, and a quinoline ring, which may be substituted with at least one member selected from the group consisting of a halogen atom, a hydroxyl group, a cyano group, a nitro group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a phenyl group, an alkylamino group having 1 to 4 carbon atoms, a dialkylamino group having 2 to 8 carbon atoms, and a halogenalkyl group having 1 to 4 carbon atoms.