This invention provides a compound suitable as an encapsulating material for electronic devices and having a high Tg, low moisture-absorptive, high adhesion and rich fluidity, which is a cyclopentylene compound represented by Formula (I) and its intermediate cyclopentenyl compound represented by Formula (III). In the formula, m is 0 or more, Ar1 and Ar2 are each a phenol residual group, a naphthol residual group or a fluorene derivative residual group, and each contain a hydroxyl group or a glycidyloxyl group.