L$_{12 }$represents an alkylene group, an alkenylene group, a  bivalent aliphatic hydrocarbon ring group, a bivalent aro› matic ring group or a group composed of a combination of  two or more of these, provided that the hydrogen atoms of  these groups are partially or entirely substituted with a sub› stituent selected from among a fluorine atom, a fluoroalkyl  group, a nitro group and a cyano group, and provided that in  the group composed of a combination, two or more groups  combined together may be identical to or different from each  other and may be linked to each other through, as a connecting  group, ---0-, -S-, -CO-, -SO$_{2}$ -,  -NR- (R rep- resents a hydrogen atom or an alkyl group), a bivalent nitrog› enous nonaromatic heterocyclic group or a group composed  of a combination of these; and  Ar$_{1 }$represents a bivalent aromatic ring group;  each of X$_{12 }$ and X$_{13 }$ independently represents a single  bond, ---0-, -S-, --CO-, -SO$_{2}$ -,  -NR- (R repre- sents a hydrogen atom or an alkyl group), a bivalent nitrog› enous nonaromatic heterocyclic group or a group composed  of a combination of these;  L$_{11 }$ represents an alkylene group, an alkenylene group, a  bivalent aliphatic hydrocarbon ring group or a group com› posed of a combination of two or more of these, provided that  in the group composed of a combination, two or more groups  combined together may be identical to or different from each  other and may be linked to each other through, as a connecting  group, ---0-, -S-, -CO-, -SO$_{2}$ -,  -NR- (R rep- resents a hydrogen atom or an alkyl group), a bivalent nitrog› enous nonaromatic heterocyclic group, a bivalent aromatic  ring group or a group composed of a combination of these;  X$_{11 }$ represents ---0-, -S-, --CO-, -SO$_{2}$ -,  -NR- (R represents a hydrogen atom or an alkyl group), a  bivalent nitrogenous nonaromatic heterocyclic group or a  group composed of a combination of these;  each ofR  11 , R  $_{12 }$and R $_{13 }$independently represents a hydro- gen atom, an alkyl group, a monovalent aliphatic hydrocar› bon ring group, a halogen atom, a cyano group or an alkoxy› carbonyl group;  in general formula (I),  It  is an object of the present invention to provide, in view of  the above-mentioned background art, an actinic-ray- or radia› tion-sensitive resin composition that simultaneously satisfies  all the requirement for sensitivity, resolution, pattern configu› ration, line edge roughness, resist aging stability and dry  etching resistance in especially the lithography using electron  beams, X-rays or EUV light as an exposure light source.  It  is  another object of the present invention to provide a method of  forming a pattern using the composition.  The present invention in its one aspect is as follows.  (1 )An actinic-ray- or radiation-sensitive resin composition  comprising a resin (P) containing not only at least one repeat› ing unit (A) that when exposed to actinic rays or radiation, is  decomposed to thereby generate an acid and is expressed by  any of general formulae (I) to (III) below but also a repeating  unit (B) containing at least an aromatic ring group provided  that the repeating unit (B) does not include any of those of  general formulae (I) to (III),  [Non-patent reference 2] Proc. of SPIE Vol. 6923, 692312,  2008.  [Non-patent reference 1] "Fundamentals ofnanoimprint and  its technology development/application deployment› technology of nanoimprint substrate and its latest technol› ogy deployment" edited by Yoshihiko Hirai, published by  Frontier Publishing (issued in June, 2006) and  Non-Patent Reference  DISCLOSURE OF INVENTION  Patent Reference  PRIOR ART REFERENCE  -continued  (II)  (III)  4  3  US 9,052,590 B2  [Patent reference 1] Jpn. Pat. Appln. KO KAI Publication No.  (hereinafter referred to as JP-A-) 2004-158287,  [Patent reference 2] JP-A-2008-162101,  [Patent reference 3] JP-A-89-325497,  [Patent reference 4] JP-A-Hl0-221852,  [Patent reference 5] JP-A-2007-197718,  [Patent reference 6] International Publication No. 06/121096  (pamphlet),  [Patent reference 7] JP-A-2009-93137,  [Patent reference 9] JP-A-2008-133448.  [Patent reference 8] US Patent Application Publication No. 15  2007/117043, and  (I)  R11  R13  I  I  --+C-C+- 1  I  R12 X11  I  L11  I  X12  I  Ar1  I  X13  I  L12  I  Z1 