The heat- or energy ray-curable composition for members contains an onium gallate salt having a specific structure. The invention is a heat- or energy ray-curable composition comprising a cationic polymerizable compound and an acid generator containing an onium gallate salt represented by general formula (1). In formula (1), R
1
-R
4
are each independently an alkyl group having 1 to 18 carbon atoms or Ar; however, at least one is Ar; Ar is an aryl group having 6 to 14 carbon atoms (not including the number of carbon atoms in the following substituents); some of the hydrogen atoms in the aryl group may be substituted by alkyl groups having 1 to 18 carbon atoms or the like; E represents an element of valence n of group 15 to group 17 (IUPAC notation); n is an integer of 1-3; and R
5
is an organic group bonded to E.