an electron beam, an X-ray or an EUV beam is used as an  exposure light source.  wherein a content of a group capable of decomposing by  the action of an acid is expressed by a number (B) of a  repeating unit having a group capable of decomposing  by the action of an acid in the resin and a number (S) of  a repeating unit having an alkali-soluble group which is  not protected by a group capable ofleaving by the action  of an acid (B/(B +S)), and the content is from 0.05 to  0.40.  the resin (P) further has a repeating unit (C) represented by  the following general formula (VI):  7.  The radiation-sensitive composition according to claim  each ofR$_{01}$, R$_{02 }$and R$_{03 }$independently represents a hydro- gen atom, an alkyl group, a cycloalkyl group, a halogen  atom, a cyano group or an alkoxycarbonyl group, and  R$_{03 }$also may represent an alkylene group and be bonded  to Ar $_{1 }$to form a 5-membered ring or a 6-membered ring;  Ar$_{1 }$ represents an aromatic ring group; and  n represents an integer of from 1 to 4.  the resin (P) has a weight average molecular weight in a  range of from 1,000 to 100,000.  9.  The radiation-sensitive composition according to claim  6,  wherein  8.  The radiation-sensitive composition according to claim  7,  wherein  10.  The radiation-sensitive composition according to claim  6,  further comprising a basic compound.  wherein  6,  wherein  14.  The radiation-sensitive composition according to claim  6,  wherein the repeating unit represented by the general for› mula  (I)  is selected from the group consisting of the following  repeating units:  13.  The radiation-sensitive composition according to claim  6,  wherein at least one of Ar$_{2}$a to Ar$_{4}$a in formula (III-1) is an  aryl group having an alkoxy group as a substituent, or at least  one ofAr$_{2}$a andAr$_{3}$a in formula (III-4) is anaryl group having  an alkoxy group as a substituent.  12.  A pattern-forming method comprising steps of forming  a resist film using the radiation-sensitive composition accord› ing to claim  6,  exposing and developing.  11.  The radiation-sensitive composition according to claim  6,  wherein  180  US 9,217,919 B2  179  -continued  oyo~ 0  oyo~ 0  ~  oyo~ $_{0}$A)  oyo~ 0  Roi  Ro2  I  I  *---f-C-Ct-*  I  I  R03  Ar1  ’(OH)n  (VI) 