A rubbery composition is prepared by combining (A) a rubber component, (B) a cellulose, and (C) fluorene compound having a 9,9-bis(aryl)fluorene skeleton. The fluorene compound (C1) may be a compound represented by the following formula (1):

##STR00001##

wherein a ring Z represents an arene ring, R.sup.1 and R.sup.2 represent a substituent, X.sup.1 represents a heteroatom-containing functional group, k denotes an integer of 0 to 4, n denotes an integer of not less than 1, p denotes an integer of not less than 0. The rubbery composition has improved mechanical properties such as strength, elongation, and hardness.

A seal member includes silicone rubber mixed with a polyrotaxane. The seal member includes the polyrotaxane in an amount of 3 to 10 parts by mass per 100 parts by mass of the silicone rubber. This configuration can allow molecules in the silicone rubber to slide on one another, so that the rubber material is easily deformed according to stress applied, such as insertion and removal of terminal metal pieces. Accordingly, scratch damage of the seal member can be reduced.

A seal member includes silicone rubber mixed with a polyrotaxane. The seal member includes the polyrotaxane in an amount of 3 to 10 parts by mass per 100 parts by mass of the silicone rubber. This configuration can allow molecules in the silicone rubber to slide on one another, so that the rubber material is easily deformed according to stress applied, such as insertion and removal of terminal metal pieces. Accordingly, scratch damage of the seal member can be reduced.