A compound represented by the formula A
F
(—COF)
n
, provided that A
F
and n have the following meanings.
A
F
: a fluorinated adamantane residue which is an n-valent group having an n number of hydrogen atoms removed from adamantane (provided that when n is at least 2, the removed hydrogen atoms are hydrogen atoms bonded to different carbon atoms), wherein at least one of the remaining hydrogen atoms is substituted by a fluorine atom, and the remaining hydrogen atoms may be substituted by a C
1-6
alkyl group or fluoroalkyl group, and n: an integer of from 1 to 4,
provided the when n is 1, A
F
has at least one hydrogen atom.