To provide a resist underlayer film forming composition for lithography that is used in a lithography process for production of a semiconductor device. There is provided a resist underlayer film forming composition used in a lithography process for production of a semiconductor device, comprising a resin (A), a liquid additive (B) and a solvent (C). The liquid additive (B) may be an aliphatic polyether compound. The liquid additive (B) may be a polyether polyol, polyglycidyl ether or a combination thereof. Further, there is provided a method of manufacturing a semiconductor device, including the steps of forming a resist underlayer film by applying the resist underlayer film forming composition on a semiconductor substrate and by calcining the composition; forming a photoresist layer on the underlayer film; exposing the semiconductor substrate coated with the resist underlayer film and the photoresist layer to light; and developing the photoresist layer after the exposure to light.