A resist underlayer film forming composition for lithography, includes: a polymer including a structure of formula (1) below at a terminal of a polymer chain; a cross-linking agent; a compound that promotes a cross-linking reaction; and an organic solvent: (where R1, R2, and R3 are each independently a hydrogen atom, a linear or branched hydrocarbon group having a carbon atom number of 1 to 13, or a hydroxy group; at least one of R1, R2, and R3 is the hydrocarbon group; m and n are each independently 0 or 1; and a main chain of the polymer is bonded to a methylene group when n is 1 and bonded to a group represented by —O— when n is 0).