Resist underlayer film-forming composition and method for forming pattern

A resist underlayer film-forming composition comprising:

• a polymer including a structural unit shown by a formula (1), and having a polystyrene-reduced weight average molecular weight of from 3000 to 10000;
• and
• a solvent,
• wherein
• each of R3 to R8 independently represents a group shown by a formula (2), a hydrogen atom, a hydroxyl group, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 6 carbon atoms, a substituted or unsubstituted alkoxycarbonyl group having 2 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 14 carbon atoms, or a substituted or unsubstituted glycidyl ether group having 3 to 6 carbon atoms, wherein at least one of R3 to R8 represents the group shown by the formula (2), and
• X represents a substituted or unsubstituted alkanediyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkanediyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkanediyloxy group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkanediyloxy group having 3 to 20 carbon atoms, a substituted or unsubstituted arenediyl group having 6 to 14 carbon atoms, or a divalent group formed by an arbitrary combination thereof,
• wherein
• R1 represents a single bond, a substituted or unsubstituted alkanediyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted arenediyl group having 6 to 20 carbon atoms, and
• R2 represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms.